7106 bridged using 4 channels to make two will run circles around a 250 all day long. Much lower distortion, more signal to noise, much more power and you will have two channels left over to play with. Remote speakers, rear speakers, a center channel if you wish, with a rear speaker or not. Its true with non Mcintosh speakers the bass will be tighter and faster. The high end is better defined too.
A 7106 will give you 300 watts+ per channel bridged compared to the 250 50 + watts. Signal to noise for a 7106 is 113 db and only 95 as I remember for a 250. Those two figures alone are like night in day difference. The distortion typically of a 25o is about .05 in the mid frequencies, a 7106 about .002% The 7106 will almost give you a black black back ground where a 250 will making noise along with the music using efficient speakers, which you will need to achieve concert level reproduction. Your choice of speakers is pretty limited with the 250 compared to almost anything with the 7106. I Installed quite a few 7106 using them as intended for HT systems or as bi and tri amps for JBL, Altec, EV and Bozak systems. They really cleaned up Bozak woofers bi amped over amps with autoformers. Its why I use 206 and 207 amps today.
I. too, like the vertical LED power meters. I am a traditionalist, but how do you put 6 or 7 useful VU meters of sufficient size on a 207. Maybe they will figure something out for a 309. How many channels do you need for Atmos, three in the front, a MC 303, 4 for the rear and sides, and do you need 4 for the ceiling or will two do to run 4 speakers in parallel? Thats 6 or 8 more channels. Yep is time to replace the 207. I guess you could use 3 303's and a 302. No wonder I don't hear anyone shouting Atmos from the rafters.