Welcome to irv2!
My wife and I own a Monoco product with a superslide. It's a 2007 Safari Cheetah 40SFD. Monoco built the frame well for the slide and we haven't had any problems with the unit. It is hydrualicly operated and we haven't had any problems with that either. The only thing that I would look at is if the unit is adjusted straight horizontally. Is either end lower than the other? Look at the molding above your storage bays to use as a straight edge. Ours actually had one low end at the factory and was not adjusted before it went to the paint shop. We had to get the stripes matched up after we had the slide adjusted. Look closely at those two things at the dealer. Monoco approved the re-painting at Gauranty RV as a warrenty item. Other than that the slide has worked perfectly.
Oh yeah, one more thing that the service tech taught me: (especially on uneven ground, but ALWAYS), Put your slides out before letting your air out if you have airbags and then put down your jacks. I saw first hand that we could tweek the frame a little bit and the center top of the slide actually rubbed on the top of the frame. This was because I tried to level the motorhome with the jacks down first before the slides were out. I know that this may sound backwards, but that is how the Monoco products are built. Believe me when I say that after bringing the slides back in and then putting the jacks back up, and starting over with the slides out FIRST before letting out the air and the jacks down, everything worked perfectly with no tweeking.
As far as how we feel about the long slide; we were first apprehensive like you but now we LOVE it.
Good luck on your research and happy hunting.
AKBrick and CheetahGirl