The F7 should be quite a ride. It weighs435# with 140hp and has a narrower track which should make it a great trail sled
The MXZ is about 470# with either the 700 or 800cc. It has 14.5" of rear suspension and 9.5" in front.
Are you asking about the Yamaha RX-1 ? If so, I'm not sure on the weight but I would think that it would be fairly heavy. American Snowmobiler called it more of a lake runner or smooth trails rather than a ditch banger for what it's worth.
You can pretty much guess what my choice would be though can't ya?