Over the last week upgraded rb122's, 133C's, 532's, 532A's, 333's, 411's (all versions), 433's (all versions), 493, 711's, rb600 and rb800.
In total 230+ units.
Most of them upgraded remotely (wireless) and most from either 4.16, 4.17, any 5.0rc version and some from older 4.xx version. Did not have one single issue!
rb133C's and 122's that became slow under 4.16 and 4.17 and some 5.xrc's are definately performing much better under 5.1. I've put 133C's on the shelf as ´back dated´ to give them now a new life again with 5.1!
This is the first time in 5 years working with ROS that an relative new upgrade worked that seemless for me!
My network is now very stable (normal routed network with 802.11a, or ´n´ links and most now also running with NV2.)
First units upgraded now more than two weeks ago in production environment and not seen a single issue since!
4.17 running P2MP networks that still had some disconnect issues became very stable under 5.1.
ROS5.1 (and 5.0) is definately much more stable than last 4.x versions if it comes down to the wireless and simple routing.
I've seen some issues with 5.x still around but these are more exotic situation with tunnelling protocols, authentication setups, 863 platform or other exotic hardware. But on the wireless I have not seen too many issues mentioned by the experiance users.
Maybe its because I use only rb's with MT radio cards in them. I've got any radio card they ever produced in my boards and none gave me problems on the upgrade.
Any major upgrade I performed in the past always left me with some units failing. This is the first time not a single board failed on me in the upgrade!
I don't know how ´exotic´ the cards are mentioned. It can be MT needs to take a look on its drivers.
Since 5.1 came in my life blood pressure went down!
Imho if you have issues with 5.1 tell me your setup. Maybe I can give you helpfull advices.