I outweigh you by 50#, and I run 11f/14r in my 29 x 3" tires. You might end up running less.
The benefit to plus tires is gaining comfort and traction without gaining rolling resistance. You go the same speed for a given effort but you gain a more surefooted, confident feel.
To me being a permaclyde (6' 6" and 230 on a light day) 29+ felt revolutionary similar to the way all you light people felt with the 29" revolution - so I would say that the + size tires are overkill for some one your size - but I would not hesitate to give it a whirl.