I have one. A 24ft, a '99 Regal (Triple E) and I don't know if I would ever have another RV without the 4x4 conversion. In all fairness, it truly does depend on what kind of camping a person does. If they are campground folks? or paved road only? naww...they don't need that. I, on the other hand..will be off on most any track I can find..mostly because I know I can get in and get out.
One thing I do want to address is that exposure on the underside, especially the rear, if a person crosses a wash-out or ditch..anything that might catch. Mine has a sheet of aluminum underneath the rear..protects the whole shebang. I refer to it as 'armour plating'. Without that I would have lost my tanks long ago.
So..mine has a 6" lift, is a shop done conversion, Dana parts..which means it can be repaired..not all builders do that...Quigley is one of those. I also put on a proper bush winch and a 12ton Warn winch. 250w solar, 3 deep cycle 12v...sixes won't fit the drawer. It's a V10 and they have lots of torgue but won't do 120k's happily. I was given a two day 4x4 course courtesy of the US Gov't..thank you very much...and the best, most important lesson? get out and look, first. The only place I haven't had the guts to go to...the beaches of Oregon or Washington.
Cost..if you want one, there is no need to spend the stupid money for a Quigley or most other shops. Mine was done at a shop here in BC..they specialize..and will convert anything you bring them. The cost was $22,000CDN..which is about..what? $15,000US? U-Joint also does the install..or used to, anyway. Yes, they sell a kit but there is still fabrication work to be done.



I have two YouTube vids that are pretty self-explanatory.
https://www.youtube.com/watch?v=FhANZhUG6WEhttps://www.youtube.com/watch?v=7ZsDmjS2XbUGary Haupt