you mean the whole crossmember conversion and engine swap or just s13 coilovers and sticking with your existing crossmember and engine???
conversion and engine swap = thumbs up from me, done it, love it handles fine with s13 crossmember, rack, LCAs and coilovers.
s13 coilover conversion = heard bad things when you mix up ae/ke and s13 bits, best to keep it all one make down there i'd say either stick with toyota gear or stick in s13, don't mix and match. only what i've heard tho