Everything that you read on all the forums suggests a 35i over the 50i as far as reliability is concerned. With that being said, how many miles, if higher mileage was it maintained by BMW or an excellent INDY shop and have any big ticket items recently been completed sparing you the cost of doing it. (hopefully).

Some people say they took care of it and still have issues. Others say that and dont really have any issues. Maintenance is a key but it isn't a guarantee.

Good luck.