It HAS been posted a bunch. Unfortunately I haven't seen more thorough testing from more technical outlets since (all of those seem to be too busy with the Switch 2 to spend time in the Go S).
I did see a much smaller channel do a three way comparison between Windows, Linux and Bazzite on the Legion Go 1 and claim some better performance, but in normal use definitely not the 2x battery life Dave2D is reporting, which is consistent with my own experience owning a Legion Go 1 with the Z1 extreme and dual booting Windows and Bazzite since pretty much day one. From that experience I'd say performance is also heavily game-dependent. Gonna guess it has more to do with hitting memory limitations than anything else (incidentally, if you happen to own a non-Deck handheld, particularly one of the more niche ones built from laptop parts with a bunch of RAM, make sure to check how much VRAM is being allocated, it can make a big difference).
It'll be interesting to re-run some of those checks more rigorously when the ASUS Ally with the trimmed-down Windows build drops.
It's an interesting talking point to me because I suspect this has much bigger reach than the devices themselves. I wonder if anybody here owns a non-Deck device, and how many Decks are even owned. The Switch 2 ended up outselling the Deck in like a week, and best guess it'll have outsold the entirety of the PC handheld segment by the end of the summer, definitely before the holidays.
I have lots of thoughts on where PC handhelds are at the moment, many of them not particularly positive, but it really feels like at this point in time nobody is talking about them as real products you may want to use and instead more as some proxy in online debate about PC software and hardware opinions.