Actually, no, the breakage is the synergy between full attack channel vamp. touch, and actually being able to hit with it. 3 vamp touches a round with on casting around hurts, I can make it 9 to 11 shots at 16th level without going outside of core+PHII where duskblade is from. TWF + 1 or 2 speed weapons of spell storing + full channel + vamp touch will annialate a lot of things without using wraithstrike.
EDIT: didn't remember that it was 1/target not 1/hit. I stand corrected. vamp touch restores lost hp before it give temporary, IIRC