Stability!
RME's drivers needed the "legacy" driver when Win 7 was first introduced.
IIRC one of the RME moderators "thanked" MS for "breaking" the firewire protocol, again!
We (the FW community) picked it (using the "Legacy" driver) up from them.
I'm surprised you're not having any problems (BSOD's, crackling audio).
Keep us posted, will you?
For now I'll stay with Win 7 until the Win 10 dust settles.
Quote from the good Doktor below:
"Nb (always worth saying) if you are running Focusrite and the latest mix control software, you should NOT be running legacy drivers any more (as they previously recommended)." What does that have to do with the FW-1884?
T