1) We love our Sabre 36QBOK. We had one of the earliest ones off of the production line - literally in the first dozen that they built.
2) We just had issues with one of our Schwintek slides that required a factory return trip. It started as a debacle and turned me into a devoted Sabre customer. Love the product + company now. I wouldn't hesitate to buy another. The plus side- the schwintek slides are no longer used on the 36QB.
3) The MegaCab- if it is pre-2013, it will have an extremely limited payload capacity. If you want to stay within your ratings, you'll likely want to look at another truck. The 36QB run with about 2,300 - 2,500 pounds of pin weight.
4) I have a bunch of pictures from a tour of the Sabre factory and they were building a handful of 36QBs in the early part of the line:
http://www.learntorv.com/2014/02/palomino-sabre-factory-tour-photos.html5) Forest River/Sabre offers a 2nd year warranty for $150. Your dealer likely won't mention it, but buy it.
6) My next camper will likely be from RVW instead of my local dealer. I'm not happy with their service whatsoever.