Let's just say, if you run Fortis's's's, you'd better keep a module in stock.
(they have gone through at least 3-4 updates, and they do get more reliable each time)
I've had bad levers in under 20 hours, and other units have gone 5000+ hours perfectly.

Once they are out of warranty, I've had good luck with opening them up, and doing the old 'make 1 out of 2' thing.

The majority of failures I see, are simply broken mini-levers.
Occasionally, you'll get 1 (or 2 or 3) that won't always sit in neutral. (it'll sit around 4% and cause 'return to neutral' errors) You have no choice but to replace. There is no other way.