I have had my 128i - Manual Sport for exactly a year now (last year, I was in Europe picking up my 128 at this time)... no regrets at all. I drove the 135 at the Performance Center - was a lot of fun, but I am sure that all that torque would just make me lazy.
The 128i with the manual makes you work hard to get to the performance - and rewards you with that sweet sounding naturally aspirated inline 6. There is plenty to get into trouble - unless you are on a track. I think its just a better balance... and comes with less potential headaches... pity, there won't be one with the new model (the 2.0 Turbo will replace the inline 6)... but that is a good thing for us current owners.