HUGE respect for Ca, Roy and Phil, been helpful to me for all my mods on 2 M5s now!
I have only once had a bad experience with a remap and it was done by AL (the company CA use) BUT I am just one of a few, MANY people here have excellent experience with them. Ahmed had soem amazing gains using Mike from AL and has total beleif in them. My experience was similar to yours with some additional issues. Since then I've always used DMS, Rob runs an E60 M5 and has worked wonders for all the different maps I've had done.
As I say, no reflection on CA, Roy or Phil and maybe I'm the only one who had negative experience with AL.
Below might be a useful link
550bhp chip tune (UK)