We are on our 2nd AMLRV (had an Adventurer previously) and have been very pleased with both.
Early on there was an 850 without slide and an 850S (w/slide). The 850 is now a slide only...actually all EC's are now slides.
We looked at a lot of SB slides and decided the EC850 was best for us.
The slide 850 is a heavy camper but properly outfitted we have no issues on a SRW. I am sure the non slide 850 would be lighter.
EC have a 3 yr warranty-one of the longest in the industry.I am not aware of any Mfr that will service out of warranty units.
Good luck, they are nice campers.
Bill