MAX7000S (EPM7128) and ATF1508AS difference?

Has anyone had experience with both the MAX7000S (EMP7128) and Atmel's ATF1508AS CPLDs? They both have a 15ns rating and should be compatible with each other but I an not finding that to be the case. The ATF1508 works for a given breadboard setup and the EPM7128 doesn't. Its the same program, the only difference is that the I program the EPM7128 with Quartus II, and the ATF1508 is programmed with ATISP6.x using the *.POF converted via POF2JED.

Once the EPM7128 is programmed, it goes throw some initialization routines and looks like its going to work, but then fails at some point.

So is the EPM7128 different in how it handles voltage or timing?

I know its sort of a vague question, put hoping someone could have some insight on this.

Thanks,

Moe