The Keil compiler sucked, so it was no surprise they replaced it with the ARM Realview compiler. My impressions were based on the UV3 front end running the gcc compiler so, no I don't think the takeover made a difference. The keil stuff seems to know more about the cpu and sets up the tools to suit, whereas the IAR requires you to set the options yourself. Fine if you know what to set! To get IAR stuff going, I have to use an example project and modify it to get everything working. Once you're at that point, it is smooth sailing. Half the problem is that each chip from each manufacturer has different startup code and that affects linker settings etc. Some have thumb only, little/big endian etc - too many options! 8051's don't quite have the same problems! Not all ARMs are equal! This can be confusing to begin with. Now they have the Cortex M3 - which is like a 32bit 8051!