I should mention that the truly lovely Studer A820 1/4 and 1/2" machine
(which is the *other* darling of mastering decks) can also lose control
of its tension sensing mechanism and "lose it's mind". I have not
experienced this first hand, but have heard so from reliable sources who
own and love these machines.
A possible advantage of the Studer is that it has a pinch roller and so
at least will power its way through tapes with little bits of residual
SSS without changing pitch. The ATR100 has no mechanism to combat
temporary speed fluctuations due to tape that sticks or drags.