The US11 inks work fine for outdoor use, and so did UH21, but I would be very careful when using them on soft materials that are exposed to sunlight.
My tests and experience shows that stickers will start to lift at the edges, curl into a roll and may even fell of over time.
Since US is more flexible, it doesn't crack and break like UH could do.
Then, like with all other inks, colors will fade over time but UV inks may be a little better than solvent for example, due to a thicker ink layer, but I still recommend varnish or overlaminate if possible.
Make the switch but I suggest you make your own test prints to see how it works over time.
Regarding 3rd party inks, even if you can find any (not aware of any for these printers), I'd say no.
My own experience with other printers over the years, is that I get dissatisfied every time I try to save some money using 3rd party inks and toners.