I have both across my bikes but will be going full tubeless. Not sure what the mess is, maybe some are more cack handed than me. I have my home brew sealant in an icing bottle and just squirt it in through the core less valve. No mess or commotion.
I have on one occasion managed to split the tyre enough that the sealant will not get me home. When this happened I just put a tube in and got on with it. I know that I have ‘punctured’ and the sealant has done its job a treat. At worst I have had to put a bit more air in the tyre to get home. No special UST or tubeless tyre here either. I fit single ply Hi rollers and leave em on till they are worn out. And believe me they are well worn by the time I take them off.
Yeah I have a small compressor at home and it works a treat with soapy water. I can’t be bothered with trying the track pump although it probably would work. I may one day try the pikey inflater just for a laugh.
I know that some have struggled to get tubeless to work for them due to various reasons. All I can say is that it has worked okay for me.