I have a round top 066 and a 394xp ,they are similar in performance with a little more torque from the 394xp but not as much chain speed.
I have not run a 661 but the 395xp is a beast all its own so I'm not sure if is comparable.
I have not run a 661 but the 395xp is a beast all its own so I'm not sure if is comparable.