Also, I have a suggestion for the storage in the 7,1. I think it would be a good idea to leave the original SSD storage alone and use PCI-e SSD storage instead. I mean to leave the original OS install like it came from Apple on the built-in SSD storage. Keep the software updated on it, but don't use it for anything. Install macOS and your personal files on your own PCI-e storage. That way you don't have to worry about backing up the original storage if you need to send your Mac in for service and there's no security concerns if you go to sell it. You simply remove your PCI-e storage.
Totally agree.
Trading-off 1 PCIe slot for more reasonable priced nVME SSD (than the proprietary storage) is the advantage of a tower form factor Computer.
A PCIe x16 card with 4 M2 slots (capable of gen 4 x4 nVME) is around 100$. Much more versatile than the upgrade kit offered by Apple.
P/S: price above is not correct. Tks to tsialex who corrected me.
Bifurcation cards (4 slots M2) are cheaper (~50$) but not supported by MP7,1 logicboard.
Non-bifurcation cards (PCIe switching) are more expensive, ranging from 200@ to 350$.
But pairing it with a pair of 4TB nVME blades at 500$ (gen3) or 700$ (gen 4) each are still much cheaper than the 8TB kit from Apple. Less hassle, too.