I only own Index controllers, not the headset. I have a mixed tracking Pico 4 setup and wireless functionality is definitely one of the pluses; the higher resolution panels also make a significant difference (the Frame and the Pico 4 seem to have the same resolution). This is basically an open Steam-backed Pico 4 that's superior to my hardware and definitely superior to the Index. Here's a comparison:

https://vr-compare.com/compare?h1=0jLuwg808-j&h2=w8xCM-oPA

The 1000hz tracking frequency is from the Lighthouse tracking system, which the Frame loses. For that and other reasons, I am not convinced the controllers are better than the Index controllers. Personally I think it's likely I will keep using the Index controllers, since I have the whole lighthouse setup and I own trackers as well.

I'm led to believe there's only so much FOV you can get out of pancake lenses? This is already spoecced to be the best pancake FOV seen to this date.

As an Index controler and Pico user: The back straps are pretty much essential for any serious use; the controller purportedly includes finger tracking (capacitive) but you can't really open your hand without dropping the controller unless you have the strap.

If as I currently intend I end up purchasing this device, I will definitely endeavour to obtain the controller straps as well as the top strap for the headset at the same time, and I recommend others do the same.

As a current and frequent user of this form factor (Pico 4, with the top strap, which the Steam Frame will also have as an option, over Virtual Desktop) I can assure you that it's quite comfortable over long periods of time (several hours). Of course it will ultimately depend on the specific design decisions made for this headset, but this all looks really good to me.

Full color passthrough would have been nice though. Not necessarily for XR, but because it's actually quite useful to be able to switch to a view of the world around you with very low friction when using the headset.

Yes, while VRChat does a lot of things right, the VRChat company definitely doesn't seem trustworthy in the long run. It's an aggressively walled garden where the company has full control over both content and narrative, and we're starting to see more aggressive pushes for revenue, with the major new features in recent months being subscription-gated or addiction bait (stickers, baubles, random reward boxes, etc). I'd love to see an open, federated VR social environment, but how do you get people to use it? Many VR users aren't technologically savvy at all.

There are currently two much smaller competitors that are perfectly usable but lacking community buy-in. Chillout, which is similar to VRChat, with some improvements the community has wanted for years, but missing some of VRChat's (admittedly excellent) homemade functionality, such as better IK code, better bone dynamics, etc. And Resonite, which is more similar to SecondLife, possessing a cross-world inventory system and in-game content authoring tools.