I have had some experience with the Muc off sealant. In fact I converted all my tyres to run it. But I have now gone back to Stans (one cup normal one cup race).
As a sealant Muc off is very good and does a very good job, perhaps one of the best for sealing holes.
But from using it over time there were a few issues than made me go back to Stans.
For a start it’s very messy to change a tyre, as stated it’s very thick and coats the inside of the tyre. So it also coats anything else it comes into contact with. I used to have to hose my wheels off after a tyre change.
It’s not as easy to reuse. I found with Stans that if you do a tyre change you could reuse most of the sealant and just top it up with a bit of fresh.
With the Muc off it’s the other way round. You can only salvage a bit and you have to use mostly fresh. Then you have to hose the tyre clean. Where as with Stans you can just wipe it out with a rag.
Finally I found that it was burping sealant out, it wouldn’t loose noticeable air pressure bit there was always splattered sealant marks up the side of the tyre. I noticed that on the inside of the rim bed, it had patches of hard dried up sealant had formed under the tyre. I wonder if this was causing the tyre to burp sealant?
My take is that it is very good at doing its job, but it’s messy and it consumes more of the product and time.
If you don’t change tyres a lot then it’s probably not an issue.