That's pretty much what I had set for my Engineer. The only differences were that I maxed out Leech instead of Wither, and I didn't spend a point for the "Placebo Protection". (I prefer to start my own games or play in public.)

For what you are aiming at, Wither is spot-on better than Leech.

When Sloucho comes out, we will likely have identical builds.

6-6-6-1
0-0-1-6
1-0