after my adventures recovering & updating my X220 with Win 7, it appears my work is going to have me get used to Win 10 after all

To recap, I got the computer recently as backup to my T410. I really like the X220 - it's small, light, and running very well, apart from an inconsistent power on issue, which occurs every so often; a member here suggested it may be due to the on button on the keyboard, and I'm planning to swap in my T410's keyboard when I pull it down for cleaning & maintenance to check this, just haven't had time... (will post updates on this in the relevant thread) It came with Win 10 installed on the original 160GB SSD, which I then changed out for a 256GB Samsung 860 pro and installed Win 7.
Back on topic: I'd like to check out Win 10 on this computer, but would like to keep Win 7 as my main operating system.
I've been reading here about dual boot setups, and I quite like the idea of having Win 10 on an msata SSD

As for the actual msata choice, installation & booting: it's proving somewhat difficult to find major brand msata's at a decent price, and I'm now considering a 128/256GB (?) Transcend 370S (https://www.transcend-info.com/product/ ... ds/msa370s). I recall reading that it's good practice to remove the main SSD when first booting to the msata?
Is there anything in particular that I should take note of when doing the setup?
ThinkPad Setup reports my bios as "UEFI BIOS Version: 8DET76WW (1.46)".
Any ideas and advice are much appreciated

Thanks,
Leon