Have to say that I agree pretty much 100% with your write-up. As a dynamic drive on twisting B roads I love the M135i. Its light and agile, and changes direction beautifully. I would prefer more initial bite from the brakes to allow improved entry speed adjustments and M cars do make the little 1 Series suspension feel slightly unrefined by comparison.
I bought the M135i as a stop gap until the new M3 was released but despite a good M4 test drive I still have the 1 series and as yet have not ordered a replacement. The M135i is just so practical and fun to drive.
Here's my M4 comparison, if you're interested
http://f20.1addicts.com/forums/showthread.php?t=1000956
Cheers
Steve