My neighbor rented my 920 for his 6620TII and it was All it could handle in 65 bushel soys. 2.5 to 2.75 mph tops, and that was on dry, level ground. The weight of the head didn't seem to be a problem.
My neighbors original flexhead (for his 6620TII) was a 216, that is until his shed roof collapsed a few winters ago and crushed it! He also pushes a 6rn in 125+ bushel corn and has no problems; - amazing capacity for a 44" machine! He ended-up purchasing another 216 after he rented my 925.
I'm using a 216 now... Would like to upgrade to a 9500 and 925. I would like to do it one step at a time. There's nothing wrong with my 6620 works great! Maybe I'll have to go to a 920. Thanks!
Most folks use a 25 with a 9500 if the ground is flat enough. I have real rough ground and use a 20 with my 9500, and it is never overloaded. It may be a little easier on the wobble box, and cheaper to maintain, and transport. If you put tall green beans through it, you might consider an orbit reel kit to keep it from wrapping, worked for me. gs