I have the same problem on my 04 4.4i. They did a software update on it back in 2006. After the update it didn't hit hard but it doesn't take off like it should on rolling stops.

If I recall correctly, the tech told me the transmission is trying to predict my next move and shift gears accordingly. If you come to a complete stop then it shifts down properly. At that time the X was new to me so I just took him at his word. Even if it is true, I have not had this issue in any other car I have own.

I hate to say it but this is the worst driving experience I have ever had. Because of it I have changed my driving habits. I now come to a complete stop before pressing on the gas. I think I will try a rolling stop tomorrow and press on the gas to see what happens. Since my X is no longer under any warranty there really isn't much I can do if the problem is there. I am not paying $4000 or more to fix this issue. I'll just have to live with it.

__________________
[Sold] 2004 X5 4.4i - Sterling Gray - Truffle Brown, Sport, Preminum, Rear Climate, DSP, Sirius, PDC, 132's (19 inch wheel), Comfort Seats
Dynavin, JL Audio Stealthbox, Alpine PDX-5 Amp