I have a pump-in-style that I bought in the US. It was about 1/4 of the price that it is in Hong Kong. We bought a small transformer that was actually meant for a camera to run it in HK--cost us less than $100 HKD. I've used the pump-in-style for two babies.
Then, I just recently bought the freestyle as going to have another baby soon.
I think they are equally powerful but the freestyle is A LOT louder than the pump-in-style. I haven't had a chance to really try out the freestyle as my baby isn't born yet but I would say for a first-time person pumping, I would go with the pump-in-style--more classic/traditional, quieter.
As far as warranty goes...I've had my pump-in-style which was bought in the US repaired several times in Hong Kong and I've also sent it back to the States for repairs. You can get most replacement parts from Celki for decent prices such as tubing, membranes etc. Have had the pump-in-style for 7+ years and it's still going strong.