Magico V-2 vs. Sonus Faber Guarneri Mementos

don't think Magico V2 is built for that room size, Guarneri Memento will be a much better fit if you are only picking from these two.

I used to own the Memento with similar room size. It will work but you may not be able to utilize its full potential. I then moved to Focal Utopia Diablo which works better in my room as the sound seems to integrate better.

Good luck!

Haven't heard the Magico V2's, BUT a few years ago we did an 'AB' of the original
Magico Minis vs. The original GH's. All preferred the GH's by a wide margin. In my room which is appx. the same size as yours, the GH's just worked a lot better. Haven't heard the Mini 2's in this room either so cannot say about that pairing.
BTW, see my review thread as to the various differences between the SF GH's and the GM's.