I've got a 240 mate. There's a bit of a discussion about the 240 on
this thread
I don't know if I'd recommend it either. It really is pushing the design limits of the engine. Some people down here reckon that the 240s don't run properly and overheat and sieze, but I suspect that it's because of poor jetting as much as anything.
The iron bore is not such a bad thing, I've realised, as it allows for cheap rebores (just had one done -- 1st oversize and two or three left).
It's up to you. My bike is very gutsy indeed, but how it stacks up next to a similar bike without the big bore, I just couldn't say. I'd advise putting your money into other performance mods first, then, if you're still not satisfied, think about a big bore.
Craig