in my experience, the benefits outweigh the (small) negatives.
you can run more than 5 psi less, the wheel will weigh 50g less and you will never pinch puncture (but these are not the only stated performance benefits).
you have to faff around with sealant, it can be messy, but the faff is considerably less than the faff of countless punctures on the trail, in the wind and rain and mud.
UST tyres cost money, sealant costs money, tubes and repair kits also cost money.
You sometimes need Co2 canisters or a compressor to pop them on the rim, sometimes they’ll pop on with a track pup, it depends.
You don’t have to wait a a good few hours after fitting a tyre for it to have sealed enough to ride on although it might sometimes go down for a a day or two till the sealant has filled all the porous bits of the tyre, on a par with a slow leaking thorn puncture in a normal tube.
i’ve heard stories of if the pressure is too low, or the tyre sidewall or bead too flexible, it can burp, roll off the rim etc, this requires you to use (shock Horror!) a tube to repair it on the trail, so you get all your riding kit, hands and bike covered in sealant, although i’ve never seen this happen in a decade of riding.
You don’t need to swap tyres over before a ride because the lower tyre pressures give you more grip in most conditions, you swap tyres at the start of winter and the start of summer.
I’ve tried it once about ten years ago and have been COMPLETELY convinced its worth it because i can feel the difference on the trail, and i have used UST rims, UST tyres, Stans rims and strips and normal tyres etc.
Some people swear at it, i say spend the money.
Just for balance :)
