The Ref 110 is a superb tube amp and a bargain for what they go for used. I saw o Hifishark that one just sold for $3200. I have had no trouble with mine since I purchased it. And I have no real desire to upgrade at this point.
IMHO 100 watts is the sweet spot for tube amps. My speakers are 92db and the Ref 110 is an excellent match. You want a bit of headroom. I tried a Ref 75 and in my system the sound was not as open. I found over time that I much prefer tube amps with 4 output tubes per channel. They don't tend to sound thin at times like some amps. My old V70 was the same way.