Seems like I read that somewhere too, I thought it was nonsense so I didn't think about it any more.
Many of the people I deal with think the 71/102/122 series are some of the most desirable of the Cub Cadet line, though a lot of people don't care for the 123. I think it's just a matter of taste.
As far as the Gear Drive vs. Hydro debate goes, that one will go on forever...
Personally, I really like my hydros for some jobs and my gear drives for others.
IMHO hydros are the best for moving snow and some other front blade work, the gear drives I like best for most other ground engaging work, I still haven't made up my mind which I like best for cutting grass.
I've been told that the hydros are nearly indestructible, I know I've run mine through the wringer AND dragged them over the coals and they are still holding up well. About the only way to tear one up is to tow it without releasing the hydro relief valves. Clean out the case, change the oil and filter and clean off the outside of the case once in awhile and it should give you years of uninterrupted service. If you are looking for a weak spot in the hydro tractors then that would be the trunion, it will wear over time and you will experience jerky starts and stops and it won't stay at a constant speed, I can't say that it is an easy fix but it is repairable and once finished it will feel like a new tractor.