Ok so, other than a (not really) panic attack when I got a blanck screen after rebooting that either solved itself or I solved by reminding my monitor that it should display the image coming from its DP cable "you know, the only one that's connected to it other than the power one), things have gone quite smooth.
It surprised my the size difference between both cards, I wasn't expecting the 1070 to lok so big compared to the 9060XT:
Spoiler!

Sorry for the dusty 1070 (and that's after cleaning it a fair bit!). It turns out that having only a front closed mesh panel is NOT a replacement for a fan filter as some say. Thankfully, I already suspected that much and, along the card, I also bought the front fan filter, because Lian Li decided to make it an accessory.
An extra bonus I didn't remember was that my 1070 used 1x8-pin plus a 1x6-pin cable. That got not reduced to only the 8-pin one.
Anyway, here are the benchmark results for Shadow of the Tomb Raider. Be warned that it's in Spanish. Not that it affects the numbers, but still:
Spoiler!
These are the settings, the same for both cards:

Texture quality to High, with the rest on Normal. Set on exclusive full screen:
GTX 1070

RX 9060XT 16GB

(I don't know what "Juego CPU" aka "Game CPU" stands for)
A bit over twice as much frames, as expected.
I'll post the GotG results on another post later.
Please excuse my bad English.
Former gaming PC: i5-4670k@stock (for now), 16Gb RAM 1600 MHz and a GTX 1070
Current gaming PC: R5-7600, 32GB RAM 6000MT/s (CL30) and a RX 9060XT 16GB
Steam / Live / NNID : jonxiquet Add me if you want, but I'm a single player gamer.