One retrofit of interest to those searching for sports seats with cars w/out active headrestraints is the possibility of getting a '09+ seat w/ active headrestraints and getting them to work. I have been researching this some as I bought access to bmwtis for a month.
MRS module would need to be changed, and it seems the one for my '08, part # 65 77 9 166 057 has been discontinued, and replaced with the one for '09s, part # 65 77 9 184 432.
One way you can check is going to an online store like www.getbmwparts.com
and searching for the part number of your unit, and see if it has been superseded. In TIS parts discontinued/superseded seem to be noted with "AE".