Trans slow to engage reverse

[kvc]

Hi all,
Hoping the collective knowledge bank can offer some suggestions regarding my dilemma.
I've had the X5 (2006 4.4) for about 4 months now. Noticed shortly after purchasing the car that the trans was quite slow to engage reverse from 'D' compared to other vehicles I've driven with a ZF auto transmission. I serviced the trans (dropped & cleaned pan, changed filter, cleaned magnets etc.) and have since changed the ATF twice to blend as much new fluid as possible in the system (using a ZF suited fluid). The fluid that came out was relatively clean, as were the pan and magnets, with only a modest amount of 'swarfing' (fine black or grey metal dust) evident.
The PO had the alternator swapped out about 3 months before I purchased the car and I've read that the six speed ZF may require a 're-flash' if there has been a big voltage drop. I have not yet done this though, as I'm quite a distance from the nearest BMW dealership, and believe this must be done via their diagnostic system???
On occasion, the transmission seems to 'hunt' or 'bump' a bit, when I'm cruising at urban speed limits (with little throttle pressure), as if it's changing between 3rd and 4th all the time. At first start-up (when cold) the transmission seems to 'hold' 1st gear for a long time, then grabs 2nd gear quite harshly. If I warm the car up (say for 1 or 2 minutes) this symptom doesn't seem to happen and all gears change smoothly. Again, these symptoms seem to correlate with what I've read about the trans requiring a flash of the mechatronics, but no where have I read anything about the delay in engaging reverse from drive - it takes like 1 or 2 seconds and is most disconcerting when I'm trying to parallel park and have a queue of cars behind me waiting to pass.
Any advice or suggestions from those who may have suffered similar problems would be greatly appreciated.