Here are my setups with it:
TP:
WS:
Barrage: (not focused on 5-hit, just use my normal barrage set so ignore main/ranged)
As stated above, it's 40-45%, not quite sure yet since I haven't done any huge sample sets (find me bullets on the cheap and I'll do it lol)
Actually the big advantages over KC+HF+1 are:
1) You can use Velocity Shot full time
2) Despite RNG accuracy bonuses, capping acc with a club is just plain hard to do even with sushi
3) As you said, your TP gain is accompanied by crushing amounts of damage.
Drawbacks:
1) Not affected by Haste/Marches/Haste gear.
2) No auto-ranged means you have to be smart about timing your attack
3) Any melee will engage a mob and hit it before you are able to shoot, since you have to wait first before dealing damage.
All in all though I couldn't be happier with it. Go here to see some detailed discussions about it:
http://www.bluegartr.com/forum/showthread.php?t=90728&page=40