We've had our SleepEZ mattress for almost 3 months now...
I did a tremendous amount of research through mattressunderground.com and other similar sites. I went so far as to have a spreadsheet laying out all of our potential mattress supplier options. Out of all of them, Sleep EZ had the longest track record, and excellent warranty, no negative feedback that I could find and a well laid out and easy to understand website. When I interacted with their reps via chat or phone, there was no sales pressure, courteous and they addressed all of my questions and concerns.
I dealt primarily with Sterling and Jeremy who have been exception in handling out mattress buying and owning experience. The post sales support has been fantastic. All in all, Sleep EZ was a pleasure to deal with and we're very happy and mostly importantly, comfortable in our new bed.