I got my used MP 6,1 12c 32GB RAM D500 512 GB SSD for a bit above 1500€ a few months ago, which at the time was less than all other offers from reputable sellers.
After some teething problems (cloning the boot drive from my MP5,1 wasn't such a great idea, and I had strange RAM problems, which turned out to be a bent pin in a slot), it has mostly been a smooth ride. That little machine must have been frustratingly limiting for some pros, but for the enthusiast who can live with its performance enveloppe, it is a nice, clean and quiet little workhorse.
The geek in me ended up buying an eGPU enclosure to host the spare RX580 then Vega 56 I had around, but of course you loose the almost total quietness of the MP 6,1, even if my modded Razer Core V2 is actually pretty quiet too. eGPU operation in Catalina has also been trouble free for me (you need to use the purge-wrangler script of course), its is plug an play and sleep/wake have not been affected.
But to be honest, unless you're gaming or doing 3D rendering, you're probably going to be fine with the stock GPUs.