They reformulated the 615 to keep up with the competition. The Azenis went from being "the tire to have" a few years ago to being "a good cheap tire, but there are better options for just a little more money".
So, now the Azenis should be on par with the competition in both grip and price.
I think the Dunlop Star Spec is the new "Azenis". Seems to be cheaper than the other "maximum performance tires" currently available.
Lemons South 2008 - Fail, Lemons South Spring 2009 - Fail, Lemons Detroit(ish) 2008 - Fail, Lemons South Fall 2009 - Fail, Lamest Day 2009 - Fail, Miami 2010 (Chump) - 2nd!, Sebring 2010 (Chump) - Fail, Cuba 2010 - Crew Chief, Roebling 2011 (Chump) - 8th!, Sebring 2011(Chump) - 19th!