I'm going to disagree with quite a few of the answers you already have
Don't get hung up on the open shifter, the old style closed shifter is excellent on the Elise and having had both I actually prefer the closed one. It would be a different story if you were buying a V6 Exige - on THAT car the open shifter is a huge advantage.
Remember that on the Elise Cup, with the closed shifter you also get the much more extreme aero which to my eyes looks fantastic, although not to everyone's taste!
For my use (Elise) aircon is a complete waste of money and is in fact a liability in terms of weight and reliability. The system weighs around 15kg (from memory) and is renowned for developing expensive problems. The Elise doesn't get hot in the cabin at all, different story for the Exige V6 which certainly does get very toasty!
220 Vs 250 - the big advantage (for me) of the 250 Cup is the extra 500rpm on the rev limit when compared to the 220.
However, the 220 engine can be aftermarket tuned to about 260bhp, the 250 engine is stuck at 250 because AFAIK nobody has yet cracked the ECU.
V6 Vs Elise - both great cars, the V6 is more expensive to run in every way, particularly on track where it guzzles fuel and is a lot heavier on brakes and tyres. Having said that it's also quite a bit faster ON THE STRAIGHTS. not so sure in the twisties! The Elise is like a scalpel, the V6 Exige is like a bloody great sword
I can't comment on your V6 Vs Elise dilemma, you really need to drive them both, I've had two V6 Exiges and I went back to a 250 Cup because I much prefer the way it handles on a twisty road. If I was looking for an Elise I would go for a used and bog standard 220 (best value) or a 250Cup (just best)