Personally my 661 sees all the action time because I like it's feel so much more... my 394 sits unless I am milling.
The slight torque advantage is highly debatable, I used to think the 394 was stronger, but running the same chain on a 36" bar on both recently (with an adaptor on husky) the 661 runs away with the cake. Just my 2c. 394 does oil better.
I can run the 661 day in day out & not lose steam, but 3-4 hrs in with the 394 & I am hating it. Scales won't tell you how much heavier the 394 feels at the end of a lond work day vs. 661. Could be antivibe, could be my body geometry.