I have heard both and previously owned the Legacy Focus SE speakers. The two are very different sonically. Legacy is a more musical speaker with an overall lower tonal balance, but it is just a little harder (not impossible) to get endgame separation and imaging from them. Focal are more “hifi” sounding and need very good electronics for them to sound their best. Their tweeter can be very resolving and fatiguing without quality electronics, and it is easy for Focal to sound “tipped up” if they are not paired with proper electronics or set up properly.
I’m surprised about your comments on the Legacy Signature SE. How big is your room, and what amp do you plan to pair your speakers with?