I'm considering the purchase of an IDE / C package
1) All IDEs are a piece of crap, so do not pay any attention to that 'feature' Evaluate based on the compiler only.
2) I believe that Keil makes a very good compiler and based on what I have heard Raisonance is about equal. If you can get by with 32k the offer mentioned in a previous post is what I would recommend.
3) A rarely mentioned mid-priced compiler is HiTech (do not confuse with Hitex) which I used at a previous assignment, I measured it as being 2-3% less efficient than Keil but a whole lot cheaper.
4) this is an unsubstantiated perception, if someone can (dis)prove it please do so I believe that IAR makes their compilers on a 'template' and thus does not come out with the best solution for anything. Keil and Raisonance, for instance are directly targeted to the '51 without any 'universality'.

Erik