Update on my Ulys tag - did 3 weeks in France in September - tag worked fine except at one entry point; I reversed and tried the adjacent one but no luck. Took ticket and paid per normal. Apart from that everything worked as advertised.
Agreed that avoiding the faff of paying through the wrong car window is worth the €2/month used fee on its own.
You can change the vehicle registration in the app, but not sure if that automatically changes the Class - car (Class 1), motorhome (Class 2) or bike (Class 5). Classes 3 and 4 are trucks I think.
Their App is in English (mostly, the Help pages auto-translate after a few seconds); the bills are in French but straightforward to understand. Direct Debit works fine.
All things considered, a good company - does what it says on the tin which is rare these days!
UPDATE - today I had an email from Ulys saying I hadn't used the tag in 8 months and when I get to 14 months' non-use, they will charge me a non-use fee of €10! WTF?
I don't know if that will be the case every 14 months thereafter. No indication of how to stop this, but I suspect I can post it back to them (maybe).