I would agree with Mister T.
There is a small chance that it could increase wear as it will be using a smaller range of the shocks movement, but it's surely within the range that BMW intended. Many, many users on here use these springs and it's not often I've read of the dampers wearing out. Worst case the standard dampers are not too pricey.
Personally I would take the chance, a set of 4 Eibachs from ebay aren't that much more than the cost of a pair of rear springs from BMW, the ride is no worse in my opinion, it improves the looks and being a thicker steel the coils are less likely to break again.
Regards, Dave