Debating between Mcintosh SS or tube monos.

300 watts of tube power puts out a LOT of heat, that would be my main consideration on big tube amps.

I have a pair of MC611s fed by a C2700. To my ears, I ultimately have a 600W tubed system. I have not heard the 2301s, but I question whether they would provide the bass control of the 611's. I have always been a fan of tubes, but after I assembled this system, I am not going back. 

The 2301s provide a touch more sweetness and dimensionality to the presentation than SS. SS has a slightly tighter bottom end, but the 2301s certainly do not lack for bass. I must confess to being a tube fan who in my prior system chose Mac tubes over SS. A 4 year old well cared for pair of monodsis no issue as long as the tubes are not too old. Worse case, replace the tubes.

Tubes are kind of a pain to track down and buy. They generate a good bit of heat. You really have to be ready to commit. The 611s is not harsh at all. I have not heard the 2301s.

I heard the 611s with a tube 2700 preamp on a pair of 802D4s. To me the 802D4 is a bit of a harsh aggressive speaker but it seemed fine on that combo. Very detailed while a bit thin in the upper mids (speaker issue IMO).

I think McIntosh tube amps/pre are a little less “tuby” than some brands.