I find this sentences very weird:

"the hardware was basically dying, choking on the all the heavy backup traffic that wasn't built to handle gracefully"

Its cleary hardware degeneration nothing to be philosophical about. Its a silicon which routes traffic. It shouldn't 'choke on any type of traffic and it shouldn't die because of it.

Otherwise i'm still not switching to 10g due to energy consumption. Its the switches which need more (if you use copper) and the client ports too.

But i only have one big machine which I do backups to and not even regularly enough that it matters too much.

Fancy hardware isn't more fun if you don't use the features. Spanning tree didn't work properly in my setup. At the end I only use vlan and the whole chain needs to support it. And the only reason for that is dataprotection: Not trusting random shitty IoT devices and i do not want to give them access to my local network.

I do like ubiquity. The switch and Acess Points have great price point and work very well and in comparision to other manufacturres an actual usable good UI.

You don't need two fans to keep a 10gig switch cool. Trick is to be careful with which RJ45 to SFP+ transceivers you buy - they come in hot and not so hot flavour. The ones I've got run at ~60C without any cooling whatsoever.

Tricky bit is the labelling on these tend to be rather rubbish esp on aliexpress so hard to tell what the chipset inside is or what the wattage is.

Nice score on the used switch! I used a 10GbE Mikrotik up until recently until it started having hardware failures (my second one, a few years older is running perfectly, been very happy with it). I got exceptionally lucky finding a used 64 port 40/100Gbps enterprise switch on ebay for $1000CAD (same switch here normally goes for $3-4k CAD used). Most of my ceph cluster is limited to 10Gbps (onboard RJ45 for 4/5 nodes, and the PCI-E slot on each is taken by NVMe drives), but I feel I'm already outgrowing that speed, my few nodes already saturate 10Gbps - NVMe drives are fast! Now I just gotta wait for 100GbE NICs to come down in price, I'm not sure I'm ready to buy a used NIC yet (was nervous about the switch, first used piece of network gear for me), but the knock off Intels are like $350 minimum here for a 2 port.

fyi zyxel has some reasonably priced 2.5G/10G base-t switches with or without poe++. I got myself XS1930-12HP when I updated my home network to wifi6 and 10G. The biggest annoyance was that some features are gated behind "advanced" license, but iirc nothing too critical. Small things, but I like that it has integrated power supply so it just has standard iec connector in the back instead of needing a power brick. I did replace the standard 40mm fans with 120mm noctua; the airflow might not be optimal but I think it'll survive.