If you watch the GCN video on the Mavic UST road tubeless, the big point of the system is the ease of mounting /dismounting the tires (no tire levers required). That's the biggest beef with current tubeless systems. If you put some other brand of tire on a Mavic rim, you lose that main feature. Mavic tires have kevlar beads, stretchier than the carbon beads of other tires.
Time is going to tell on the mavic tyres. a stretchy bead is not normally a good thing with tubeless as it can cause some refttining issues. I am sure Mavic are aware of this and therefore the bead is not actually stretchy.
Why has using a tyre lever become so difficult? Cycling it self is quite a difficult thing and yet people can't cope with using a tyre lever anymore. I remember one night with a Pacenti SL23 V1 (not known for easy tyre fitting) and a schwalbe one tubeless that let me down my lever breaking when removing the tyre (or some other similar problem maybe I forgot them) and having to remove by hand fit the tube (as there was no choice) and remount the tyre by hand. I managed somehow even though it was a cold dark january night. This is an example of tyre that I dont think is much good as it let me down (literally) like clockwork.
Why does anyone want to take the tyre off and clean the sealant out. Mistake!!!!!!!!!!! a tubeless tyre is meant to be left installed for the life of the tyre. you remove it to replace it. the problem with tubeless is not the technology or the ease or difficulty of tyre fitting. It is simply end users making life hard for themselves.
yes presta valves get bent but if it breaks as they do sometimes then you simply put a new one in. Again where is exactly is the problem with that. all you need is a valve core and a valve core remover, it's easier than changing a inner tube.
Given I fit tubeless tyres every day with levers I would add, most of the time I can say it take no longer to fit the tyre than it does a clincher with tubes. What take the time is fitting the rim tape tape, fitting the valve, first inflation to seat the tyre, injecting the sealant and finally the second inflation to refinflate it after the sealant is added. Mavic'seasy UST system will not speed up the process as the tyre fitting time as it is already quick, and that with every tubeless tyre on almost every rim that I have tried. I think this is the real reason why it wont catch on as many of the problems identified in this thread are not problems in my eyes and in many cases are simply inexperience.
Although having tyres that mount by hand is nice so it is not unwelcome either.
Strangely I've had great experience with Pro Ones on V2 SL23s. Mounted by hand, inflated with a floor pump, haven't had any issues since.