I'm in the process of converting my 4x4 saph to 2wd at the moment.
When it was 4x4 I was running 450bhp so it wasn't exactly a slouch but found it very boring towards the end so while the engine was coming out for a rebuild, I thought I'd convert it to 2wd.
Last year, a mate lent me his stage 3 moonstone 2wd saph for a few days and I just found it a lot nicer to drive and a lot more fun!

Thats what swayed me towards converting to 2wd.
Tbh, both 2 and 4 wheel drive have thier good points and bad points IMO.
With 2wd, the gearboxes are very strong as standard, I find them a lot nicer to drive, a lot easier to work on etc but you do have to respect them a lot more as they do bite!! Lol!
With 4x4, they are more sure footed on the road as you would expect but the transmission is a lot more fragile than the 2wd stuff and there is more of it to break not to mention the cost of upgrading all the parts.
So I guess it all boils down to what you actually want to achieve from the car. For me at the mo, I'm gonna vote 2wd!