I purchased the BA encampment with the insulated pad, the system works well for me. but, I have had a few problem along the trail, such as, at laurel gap with temps in the teens the zipper became stuck & eventually broke during the night, causing an influx of cold air. I had to compensate by using my footprint to cover myself during the night and sacrificing condensation for warmth. REI did replace the bag without any problems.
also the other things I have found is that the pad extends the feet area of the bag in a wide open position, again, I have to compensate by stuffing the bottom of the bag with extra clothing during the night.
the pad :all I can say, is that is gives me some of the best sleep that I have ever had out there.
what do others us & how good or bad do they work?

I own the Big Agnes Lost Ranger and have had no complaints. I agree, the inflatable sleeping pad that slides into the back is awesome. The best part about the pad is that it's locked in place so that you don't constantly slide off.

Cobb

I have the Big Agnes Zirkel and the Lost Dog. The Lost Dog is a 50+ rated bag that I use alone in summer and it slides over the Zirkel in winter to allow me to go to lower temps. I will never need another bag. Hands down the best bag I have ever owned and will buy another when this one breaks. No problems here. Just sweet dreams and ultimate comfort. I have the Uninsulated bag...they were just coming out w/ the Insulated when i got mine. I need to upgrade.