I pulled into a gas station ...
Sounds successful to me. I'm not a great rider and I'm especially poor at handling a motorcycle at high speed with a flat tire - I've even got the scars to prove it. I'm not that concerned with how easily Slime comes off to allow a vulcanized patch - either the hole is plugged by the tire sealant and the tire runs and wears fine - or you replace the tire. I mostly would consider it a success if it holds air long enough for me to detect that I have an issue and get out of traffic. I check my tire pressure all the time anyway, so if it will just hold enough pressure to keep the tire on the rim and the bike semi-controllable until I can tell I have a problem and stop, or until I stop and check my tires anyway, I'd figure it was ten bucks well spent. If one of these newer formulations work even better at plugging holes than Slime - I'll switch.
I don't know if that British Fishwick guy had any real information or not about the Slime separating at high speeds and then not working - and I personally have never been chewed out for using the stuff although I am blest by being pretty hard to insult.
Were you using their "Spair" kit to fix a flat? Was it still bubbling when you hit the station or had it managed to seal the hole? How far did it get you? With a car, I've gone 60-70 miles with tires that were done-for. If the hole was small enough for it to plug with Slime and the belts didn't seem to be damaged, I would have just filled the car tire up with air, driven it ten miles - rechecked pressure - refilled - and repeated until it stopped losing air or until I got home.
As for the balance issue that seems to concern most people. I think the balance is not much of an issue with sealants, and I'm probably a worst case user for application. I go heavy on the rear at about 20oz (use most of a 22oz car bottle) and light on the front at about 8oz (half a 16oz bottle). That's a low-speed recommended dose on the rear and a high speed recommended dose on the front. With my dose in my tires, and with my bike stored inside overnight (reasonably warm) I can feel something only for the first couple miles. If I leave the bike outside and it gets freezing, or if I don't ride for a week, I can feel something until I hit the freeway about 14 miles away. (my commute is 80 miles each way and the first section is on a highway through town at speeds from 0 to 60). The vibration is not bad - just barely detectable over the medium-low quality paving in this area... which I would say is about average-bad. Oregon DOT isn't corrupt like NY/NJ, but they aren't very competent either... After that, it's undetectable.
The Slime people say:
1) Motorcycle tires are manufactured to very high specifications and are true to round. Our test results prove that adding rotating mass such as SLiME has limited or no affect on balance
2) You could simply install sealant in the rear tire. Although we recommend 8 ounces per tire, the rear tire is quite a bit larger and wider and can be treated with slightly more product; 10 to 12 ounces. Most flats occur in the rear tire. Generally, the front tire sets up the puncturing object and the back tire picks it up.
3) If you would prefer treating both tires, installing no more than 6 ounces in the front and between 8 - 12 ounces in the rear (depending on tire size/width) will provide flat protection and reduce balance related issues.
So I'm way over their recommended dose which seems to be limited to minimize balance related issues.
This is what the Slime people posted about balance and performance on motorcycle tires which is pretty impressive - they say the stuff worked to 150mph with a 1/4" hole: