Within practical limits, you cannot have too much power. I have a pair of Magnepan MMG that were for some time driven by a PS Audio GCC-500. That's 1000 Watts per channel into the 4 Ohm load of the Maggies. I think that was 'enough' power, as I never got to maximum volume before my ears said 'that's enough'. That amp developed a fault and needs service, so in the meantime the Maggies are being driven by a PS Audio Trio C-100 (200 Watts per channel into 4 Ohms). The C-100 also has sufficient power to play well with the Maggies. Unfortunately, I cannot tell you that one or the other amp sounds better as I did not do any critical listening and comparison while both were operational. Still, more power did not hurt, even if I cannot tell you that it sounds better.
That said, if I had the funds, I would not hesitate to (and would very much like to) buy a pair of Vidars to operate in monoblock mode into the MMGs, and would comfortably suggest the same for any Maggie owner under the following conditions. If you can get things as loud as you want running a single Vidar in stereo mode, then you should have no difficulty in running the Vidar in monoblock mode. You will have four times the headroom (much better for transients and overall control) while averaging half the power delivered per amp. This would be the same power per channel at the same listening level, therefore half the power per chassis in monoblock mode. You would only hazard running into protection if you were power limited in stereo mode needed the additional power to be running the sound level more than 3dB louder in monoblock mode than in stereo mode. While not 'rated' into 4 Ohms (that's a legal/FTC rating issue) the Vidar should be safe operating into that load at the same listening level that it can deliver in stereo mode.
J.P.