I have a low options sport line xdrive 28i which I really love and I think it is the better price point for the X1 (the $1900 sport line is too much $$ too IMO but I want the sport seat with all season tires...). Once you add it up to $40K+ it become a different market where you have more choices.
A loaded 28i is too close in price to 35i which is a tough choice. Yes a 28i does 33mpg on paper but unless you cruise on the flat hwy all day long it will never hit that. It may not be too far in mpg from 35i if you like to drive fast all day. On the other hand I drove both 28 and 35 I found that if you manual shift both and pedal down they both feel just as fast. The problem with 8 speeds is if you leave it at D it try to up shift as soon as possible to save gas ; and that feel gutless. Of course the engine of 35 sounds so much better than 28 but the 8 speeds shifter look so much more modern. 28 is lighter car mean it is better in handling, but 35 have a better brakes! I believe 28 will have a better resale value if the gas price keep going up (rather it make 33mpg or not in real world it is 33mpg on paper after all) but I also believe the 'old tech' 35 would be more reliable... like I said, tough choices!!!!
To me X1 is not about all the tech and features (you can get a Ford Escape with all the toys you can think of for $35k), it's about getting that BMW driving experience while it's still practice and at a lower cost than other BMW lineup. And when I say the driving experience I mean the old school BMW way not the new water down disconnected way.
Just my 2 cents...