Here in Canada we have had the X1 for a couple years now. I started test driving the 2012 X128 last year with the 8-speed auto. We really wanted a manual transmission and thought we would have to put up with a boring automatic transmission. One block with the X128 and I knew we could live with that transmission. It is energetic and exciting.
We were at the dealer two weeks ago (after our 5th test drive in the X128) custom ordering our new baby. I remembered seeing an X1 very similar to the one we were spec'ing already on the lot, so I asked about it. It was the X135. We didn't want the larger engine and 6-speed tranny, so we continued with the order.
Our salesman (saleswoman Eve actually) read us like a book. She told us to take the X135 for a little spin in the parking lot. Since it hadn't gone through PDI (Post Delivery Inspection, I think) it could not be driven on the road. So we tooled up and down the parking lot a bit. Reving up to 4000 RPM in a parking lot with 300 hp under the bonnet was incredible. With their one year anniversary sale (BMW Langley, BC) our custom ordered X128 was the same price as the X135 already sitting on the lot. So we bought the X135 and have put on 900 km of the 2000 km break-in period (under 4500 RPM for 2000 kms). It was the first X135 sold at that dealer.
If the X135 had that 8-speed transmission, I think it would fire through the gears too quickly. As it stands with the 6-speed transmission, you get a low first gear and well balanced taller gears. It still feels like it shifts a lot to give you the power you need, but nearly as much as the X128. It actually feels a little bit like the 1991 Alfa Romeo 164S we used to have, beautiful power from low revs all the way up to ... well 4500 RPM.
Also, the X128 had the electronic joystick shifter. It was fine, but I don't think my Mom could borrow the car because it'd be too complicated for her. I know my Mom would have been able to drive somewhere, and stop, apply the e-brake, and not know how to put it in park. She could turn off the engine but not be able to take the key out because it's not in park. She would then call me to say what a stupid vehicle I have and then make me come down and show her AGAIN how to park it.
The X135 has a more conventional mechanical shifter. Press the lever and move the shifter into D, done. Compatible with my mother's 65 year old brain.
So to sum up this boring tale:
1) The X128 has a fantastic engine and energetic 8-speed transmission,
2) The X135 has a massively powerful engine and a well suited 6-speed transmission.
3) Test drive them both!