as I said, it is just like with tire or oil threads: who has used it knows it, others rely on opinions, mostly of people that have never tested it. most of these articles on the web are written by people who have never tried the product but rely on "official" tests. I am working for an american Software company. We have done so many tests against competitive products to show ours is better, so I know how it works...: You look for a niche where your product fits best and the other product has a challenge and that is what you test. Or you do it like one of our competitors: you simply claim you are #1 on the market and over time, people do believe that and with that, they request that product and you become #1...
Back to Slick50...
I had cars where Slick50 showed almost no result and I had bikes where it had so significant and obvious results that nobody could deny it. And it is a repeatable result in every Laverda I used it on, but not with the same grade of result. Engine age, condition before the treatment etc. is influencing the outcome massively. The first was my Jota, mid of the 90's. The bike was a pig to ride, almost impossible to adjust and really ran like shaking a bag of beans.
I warmed the bike up, put Slick50 in and rode to the next highway and gave her a go. Only after roughly 20 Kilometers, I left the highway to turn into the opposite direction. Idle had gone up from 1.200 to roughly 2.700 revs

. I turned idle down and entered the highway again, giving her a real pul of throttle. Engine pulled more freely with every kilometer, shifting was way easier. When I left the highway again, idle had again gone up over 2.000. I turned it down to roughly 1000 (which wasn't possible before, bike simply stalled if I put it below 1200) and went home. I put on the sync tester and synced and adjusted the carbs. After that - believe it or not - I could go down to 500 revs with idle without the bike stalling. For mechanical safety I put it back to 1.000 however. As a side effect: the RR oil temperature gauge normally showed between 90? and 110? oil temperature before the treatment during normal operation, in a traffic jam it even went up to 130? sometimes... scaring... afterwards I never had the bike reaching the 100? again. Funny, eh? :
Bike ran sweet all time after that until I dropped it in 1997 and stripped it for a major overhaul and tuning, which took 3 years.
I admit this was by far (!!) the biggest improvement I saw with slick50 on any engine I treated it with. Others only improved in shifting or idle went up just some 100 revs or so. But on all engines treated with it, the engine noise went down significantly and the engine reved more freely. It is very much important though that you follow the right procedure: warm the bike up, put it in and then go for a fast round with high revs for at least 20 minutes, better longer. But DON'T do that on new engines! They need to run in first!!
To sum it up: heat went down, revs went up, noise was reduced and shifting improved, all without any negative effect whatsoever.
So - try it or not, that is absolutely up to you. If you have a proper oil-filter installed, I would go for SX6000 as they claim their particles are small enough to pass the filter. I have the washable filter installed which anyway has less restriction, so I don't expect them to end up there (and have never seen kind of "mud" in the filter to proof the theory of the particles end up there).