tl;dr version--do it.
I just tried it out. Sort of. We're the team at TWS who got punted out in the first hour with a mother-of-coco, we're-going-to-need-an-entirely-new-car, race-ending hit. Apparently there were a few talking-tos and crackdowns after we left, but looking at the impending car swap/new safety gear/repair bills meant that I wasn't in a place to spend extra cash on the second hotel night, plus the short turnaround for the 24 hour Lemons race this September meant I needed to be looking on Craigslist for a new shell...yesterday. No time!
So, with that grain of salt taken, here's my opinion on how I think the two series compare.
There's less traffic in Chump and you can get going up to higher speeds on some tracks accordingly. Just like Lemons, some teams can control their cars and others...not so much. That's always the peril of running in a series that doesn't have any real kind of prior driving/testing/licensing requirements for any of its drivers, though. Some people like the open run room, and others don't--personally, I feel like it's a different challenge. I like playing in traffic, and I like seeing what I can do on an open track. I didn't get to drive the Chump event we entered because dead car, but I don't necessarily see the limited number of participants as a bad thing. That's all up to personal preference.
There's less of a party atmosphere at Chump, but it's still fun. The people--in person--are very, very similar to the people who run Lemons. Shoot, a good chunk of us run both series.
Too bad there's not a mute button on forum fanboys--if I had only read the forums and had never been to an event in person, I'd have been a whole lot iffier about running Chump. A lot of the Chump fans tend to like that it's more about the racing than the spectacle and I understand that--I have fun just doing the racing part--but the fanboys who get super snotty about it are arrrrgggghhh. I rarely get that same attitude in person, though--and never from someone I don't know. In person, it's more "welcome!" and "thanks for trying this out!"--as it should be!
(Needs to be said: let's not ignore that Lemons has a small contingent of equally annoying fanboys, either. And they're also aaaaarrrggghhh.)
The level of driving skill (just like in Lemons) seems heavily dependent on who shows up. The Harris Hill races I'd been to before last weekend (usually on flag/tow/paddock duty of some sort, not racing) were a really chill bunch that for the most part, either knew how to drive and conduct themselves on a racetrack or picked it up really quickly. TWS last weekend? Granted, it was the first hour of the day where there's always a lot of derp as people figure out the track and the flow of things, but I saw a lot more blown flags and overly aggressive driving. It sounds like it got much better after we left, though, as stiffer penalties got doled out for the "y'all should really know better or OSB" mistakes.
To be honest, I like Lemons' "scare the crap out of everyone about the possibility of being sent home before they even head out on track" approach there. The four penalties = trailer in Lemons is a bit heavy-handed, but it seems to work. Either way, I wish the more cautionary conversations that happened about flags and contact after the morning's problems at Chump had taken place before the race began.
As far as penalties go, I'm happy to do a princess wave all around the paddock as I'm saran-wrapped to my car, but the guys who don't tend to prefer Chump's no-nonsense, time-based approach. I like the idea of not having to worry if I drop a couple wheels off or even have a four-off that I'm going to get flagged in. Shoot, I even like the idea that I wouldn't be black flagged for some other guy nudging our car--I wish Lemons would only bring in the guy who's at fault in minor taps where both cars can keep going, too. Unfortunately, this seems to lead to more aggressive driving in some cases at Chump because "woooo no penalties for the little stuff," but the faster teams seem to realize that the pavement (and not spinning out) is where it's at, and they do at least seem to make an effort to get out-of-control teams to dial it back as the day goes on.
Safety gear requirements differ a little. The biggest issue is the window nets. I'd rather trade the extra risk of flying limbs in a rollover for not having a visibility-limiting window net. Chump's gone a little net happy (even mandating roof nets on convertibles, where the easiest way to GET OUT! of a car ASAP is often through the roof!), but eh. They're mandating fire suppression systems next year--it's an added expense, but I think that one's actually a good idea. Lemons seems to have stricter cage requirements--our back diagonals in the smooshed car are now illegal in Lemons because they extended to the back of the 944's hatch, past the rear wheels. So, no love lost for that piece getting destroyed last weekend.
Chump has no bribing, so your penalty laps are your penalty laps. I actually thought their system of car valuation was a lot more straightforward than Lemons for the more popular cars to bring (at least on paper) but meh--I stick to beat-up hoopties that belong at a Lemons race and we're not really competitive on laps, either. We're here for the track time, the people and an enjoyable weekend of hoonin'. We only bribe at Lemons for the lulz.
Chump doesn't have the diversity of cars that Lemons gets. There were a few subjective-ish prizes, like the "Spirit of Chump" one that my friends in the TR6 got, but there's a lot less attention paid to crazy builds, fun themes, or the like. Again--not necessarily a bad thing, just different. We even partially themed the car and planned to save the "full retard/judgebait" version of our theme for September. (We'll still probably do that, just on a different shell. Ja.) So, an example--the same VW Type 3 that won IOE over here was really just a slow car over in Chump. That's great if you're just doing the race because racecar time, but maybe not so great if you're trying to compete for the series' top prize--you'll want to bring something quicker if you're after Chump's big prize. That being said, the series attracts car nerds just like Lemons does, so the guys who appreciated that car for what it was still thought it was cool.
So, ignore the fanboys who take their own personal preferences as the stone cold truth gospel. If it sounds like an enjoyable weekend, try it out. If it doesn't, then don't. Both are a pretty good time (well, unless your car gets totalled early on--that'll ruin it regardless of where you are) for a tracktard with a beater racecar.
