Steve, welcome. The difference in maximum power output between 125 watts and 200 watts is only 2.04 dB. For example, if at a brief peak your M80s could play it at 110dB with 125 watts, it could play it at 112.04 dB with 200 watts, a barely noticeable difference, especially at that level. Also since the output available is higher into the 4 ohm M80s, the numbers would be even a bit higher(190 and 300 watts, with the same difference of about 2db) . So yes, even in your big room the 7125 should be plenty, and the relatively small excess headroom of the 7700 wouldn't likely be used. The money almost certainly would be better spent on the other items that you mentioned.
