1. If you could, when SMG shifts from 1st (4230 RPM) to 2nd (2500 RPM) in sport mode, does it engage the clutch immediately (at about 4200 RPM) or does it try to match 2500 RPM before engaging clutch?
2. This 'kick' you are describing, is it like a sudden short burst of thrust, or like a sudden short burst of braking? Or is it like a kick to the transmission?
3. BMW information on SMG (on both 3 series and M3) states "gear shifting without lifting foot from gas . . ." Did you keep your foot on gas during shifting or did you lift?
My understanding of SMG operation from reading numerous review of SMG fitted 3 series is that it is to be driven like a race car in Sports mode. ie. Foot to the floor type of acceleration at race track or highway on ramp.
M3 SMG also, I've read, is rather harsh (abrupt & direct) in shifting in sportier modes. However, M3-SMG has 11 different modes, 6 being manual modes of increasing 'sportiness'. 3 series SMG has . . . let me see . . . 3! Automatic, Manual & Sport. I am guessing here, but I think the BMW engineers probably have only included 2 extreme modes of manual shifting, Manual = most subdued shifting, Sport = fastest but also harshest shifting.
I would try a hard acceleration gear shift test. Personally, I would accelerate very hard and shift at 6000 RPM and re-assess the kick. Let me remind you that this is YOUR car if you decide to try it out (ie. please don't blame me . . .
when something goes 'BANG'). Also, watch those speed limits . . .