The Xbox One X was and still is an excellent console. Apart from the faster load times on the Xbox Series S - I wish I hadn't sold my One X to fund the Series S with hindsight.
I was waiting on a inevitable slimmer Xbox Series X to come out as I think the big black box looks pretty shit if I'm honest. But, end of year, probably going into another lockdown... fuck it was my thinking process when I saw one for sale which did not need a bundle or other BS to buy.
I haven't decided what to do with Series S yet - it's a great little console in its own way but mine will probably end up on eBay.
PS4 Pro to PS5 is IMO a worth while jump though, PS4 games do run smoothly (even the 4k ones) and the SSD does reduce those load times by a very noticeable amount. I guess your PS4 Pro with SSD will be closer than my old mechanical drive PS4 Pro was to the PS5, but it won't totally overcome the FPS difference.
Yeah my One X's (have a gears 5 & taco bell eclipse models) I installed SSD's into them both as well. The PS4 Pro responded better to the SSD as it's less powerful than the One X is and seemed to benefit from the faster drive a bit more than my One X's did. Borderlands 3 was a great indicator on this. The Pro struggles with load times and it's quite noticeable on the inventory screens. But the One X ran it ok.
After SSD installs in both consoles the Pro did certainly improve on that. But it still wasn't nearly as good as a stock One X.
I quite enjoy my One X's still. only 'gripe' is that it can only handle a 2TB internal drive. I'd bought a 4TB SSD initially for my Gears 5 X, but ound out the OS couldn't deal with more than 2TB's so I returned it. And now that 2TB drive is 98% full..
So yeah, my Pro w/SSD & One X's w/SSD's are still plenty fine for me. They both run 4K games on my OLED just fine. Though I know a PS5 would certainly be an improvement I see no need yet to try and find one. Or a Series X for that matter. Makes more sense to wait for them to be easily available at retail, have games you actually need one to play, and have the hardware issues sorted out a lil better.
I know they've changed the cooling system on the PS5 a little since launch. Not sure if it was to lessen the manufacturing cost a bit or if it's to help it's thermal issues. But I don't think they've addressed the fragile controllers yet. Nor have I seen anything about the Series X having the power supply issue sorted out yet. Though that's not been as common as the controller issues on the 5 from what I've seen