I concur with you on this except the tube labeled stuff is better I think. I have done both and always will have this product in my bikes. I absolutely hate the ride quality of those liners as well! They are not in any of my bikes.
Wrong, I was using the regular Slime until I realized that the regular stuff doesn't handle the types of punctures you get on a pit bike when trail riding. This stuff is the same as the tube or bottle slime, except has larger chunks of stuff and it's higher viscosity so it seals better rather than being watery.
That being said, it's still water based, all Slime brand is.
Flix-a-flat is a whole different story, lol.