I played one in their shop last July, and it was a bit of an eye-opener for me. First off, the thing really played and responded easily, and just filled the upper level of the barn with sound. I should also note that I've played EB for over 50 years, and had been looking at an upright since the spring for the first time. I would not be able to tell anything about the differences between curved and flat backs, other than the flatback is heavier, which is an issue for my bad back. I was lucky enough to find the last Shen bass they sold with their setup changes, and I am very happy with it. Good luck.
Glad I woke up on the green side of the grass.