If you think you'll be chasing power then definitely get the ed30. Elaborating a bit on the remap figures above, as well as having the larger k04 turbo the ed30 has a stronger engine and can handle well beyond 400lb/ft whereas the GTI (AXX or BWA engine code) is weaker, and can only safely be tuned to around a 380-400lb/ft limit, and that must be with a good map that is sympathetic to the engine internals.
If you got a normal GTI you could tune it to a limit of around 285bhp and 360lb/ft, at which point you're limited by the k03. If you wanted more it'd become costly, but you could achieve 370bhp and 370-400lb/ft with a k04 conversion or k03 hybrid. At that point you're at the limit of your engine internals.
If you got an ed30 you could get that 370bhp without touching the turbo, just bolt on 2+ mods. If you wanted more there are all sorts of options, from a hybrid k04 like a TTE420 (TTE480 has just emerged) all the way up to a big Garrett GTX.
You could argue that beyond ~350bhp any more power in a front drive car is pointless, but it doesn't stop people trying, and having lots of fun in the process.
If I could go back and pick up an ed30 instead of my GTI I would. I've got the tuning bug and I'm working towards a k04 conversion. Also consider the fact that an ed30 should hold its value better than a normal GTI.
Get the Edition 30.