It's a good hashrate, but there's a choice to be made, maybe 2 5700xt hashing 54Mhs each one will be a better choice, with bios mod people are getting 56Mhs
Here in my country 2 radeon 5700 are cheaper than one RXT 3080 and it's easy to buy
I'll probably buy one if I have the chance with a reasonable price
The problem with 2x more video cards is management, twice more risers, twice more problems, twice more psu cables. The 3080 is easily the best buy, now yeah prices vary depending on the country but I believe once this turmoil is over, things will get back to normal and the price of the 3080 will be very close to msrp which in turn will make it attractive again.
mining rig:
1 psu: 10-12 years warranty (enough pcie for 1200-1600w models)
1 motherboard: 2-3 years warranty (3-4 pcie slots are common)
1 ram: lifetime warranty
1 boot disk: cheap, can be usb, ssd hdd.
1 processor: very high chance it won't have problems
3-4 risers: easy management
note: typically psu will run their best efficiency at 50% load, 3080 @ 100mhs 250w is 750w. with 1600w psu is very near the peak efficiency of psu, of course just tweak it out for personal preference but the setup is within the range of peak efficiency curve
Yeah I agree with everything you said, you do your homework ehhe, still, mining is a lot of work, I prefer trading, much more money and risks too. The warranty if honoured makes things easier to roi.