I can't speak for the UForces but as for general comparison between the 500s and the 800s, either are suited for slow-going as much as the other however for work, which the UForce was built for, the 800 will just have more of...well.. everything.. and IMO only, with so may reporting problems with all the 500 engines, which mange are fixed now, I just would have a hard time buying a 500 in any model and would just go with the proven 800 anyway. Now with that said, there are many reports of good and long service out of the 500s and there are many happy owners... so with an extended warranty..and some extra perks like you mentioned...and no more need then what you say.. it may be the right one for you.