If you're ITM 85% of the time, yeah, I'd go back to SNG, though if you only have a $11 BR left, you'll have a nonzero risk of busting, but odds
are you'll be fine. Your graph doesn't say how many hands you're talking about. You've won 40 big blinds, so either you're doing well over a very small sample, or you have a big sample and are winning only marginally. There's really not enough data there to say how this is going to turn out.
The bit I think always gets left out of BRM is this: Willing to deposit again? If so, then definitely go to SNGs if you're 85% ITM. If not, I'd stick to cash, which you imply you're winning, until you have some of your BR you're willing to slice off and treat as play money.