Best Developper tools for Cortex

I am approaching to the ARM world and I develop applications for Cortex 
M3 LPC17xx and in the future also LPC11xx M0 .
I have to develop in C with the libraries support.
I'm evaluating development tools to use and would like some advice from 
those already developed in this field, considering that my application 
would probably exceed 32K and not want to risk it.
I tried the evaluation version of Keil UVisions 4 where I configured the 
CodeSourcery GNU compiler, but I read that debugging is limited to 32K, 
can you confirm me this information ?.
I also tried LPCXpresso limited to 128K with the possibility of moving 
to 256k with low cost, but the libraries seem too basic and not complete 
for all peripherals.
What made the libraries better? I saw that most of the examples are for 
Keil.

So, I want opinion from those already use these processors, to be used 
as development tools at no additional cost and if so, what to buy at low 
cost.

Thanks