I have both the Grizzly Baby Drum Sander and the Jet (Performax) 10-20. The Grizz has produced maybe 35 bows, the Jet is purely backup. I don't know if there is a "perfect" drum sander... I've been looking at the Delta... pricey. My first drum was a used Performax and I got rid of it very quickly. As you note, the flex was simply unmanageable. Got the Griz and was very happy, until the feed motor drive broke. They sent a replacement free, but it took several months as they were in the process of redesign. No problems since. While it was down, the only immediate backup (like same day!) I could get turned out to be a new Jet version of the Permformax, so I went ahead in order to keep the job moving. It performed fine, but I was still nervous about when the flex in the arm would start showing up. I haven't tried it, but I think I could go thinner with it than I do with the Griz.
Grizzly's new lower price drum, which you mention, is very obviously to the same design as the Permormax, but with a brace on the open side, which has to be a good idea, but might be a pain. I have talked with a few folks who have actually modified their older Performax models by adding a brace and they say it isn't too much of a hassle.
Overall, I'll stick with my Baby Drum and the cloth backed paper. I grind down to .060 without a sled and to .050 or a bit less with a sled. I haven't had a need to go thinner than that. If I wanted really thin veneer I guess I'd just buy it.
There's one guy's experience, for what it's worth....