I am using the Tein S.Tech springs with original shocks, had them for about a year now and quite happy with them, haven't noticed any excessive wear so far. At the end of the day it comes down to the current condition of you shocks: lowered springs on factory shocks is OK, lowered springs on old worn out shocks is not.
Depends on how much lower it will be compared to stock. If the lowest point on S tech springs when going over a bump is lower than the minimum shock travel height of the OEM dampers, then premature wear will occur. It might take over 6 months to 2 years to get blown shocks, but it will get there eventually.
Another thing to keep in mind is how many k's the factory shocks have done too.
The shock shaft and seals will have a wear pattern to them after a certain amount of time, moving the shock to a different operating range will increase the wear on the seal and lead to premature failure compared to the standard height...