For raw fleshlight power, having a funsr wll be more powerfull in stroking. Even without suction, this will generaly end up being more intense. These devices just pull the sleeve directly, which is the most efficient method for stroking itself.
Suction doesnt allow allow enough power to be transmitted over to sleeve movement. It can do this to some degree, which is a good experience on its own. And the adapter should be used for just this experience.
If you care more about suction than stroking, the vacuglide will win by a huge margin. Although for pure suction, i would just use the normal receiver on it. Those receivers work much better than the fleshlight and its adapter. Again, its a diffirent experience.
But i would recommend the adapter because of that diffirence, its a relatively cheap addition that does open up a new feature.
Combining the 2 does cause a problem, which you probably cannot solve unless you set the suction to be slow (i havent tested this yet). Too strong suction will pull the fleshlight sleeve back into its case, and the vacuglide (assuming same power as tremblr) will have no problems in doing this. Thats how powerful the suction of these devices is.
And now it gets amplified if the max suction happens to be at the bottom position, and the fleshlight now gets pulled up. It combines the 2 devices in power to pull the sleeve back in.
This is anoying as its immersion breaking, and requires you to first solve it. If there was any way you can prevent this from happening i would definitely like to know that, but that does most likely require some specialized equipment to avoid this problem (some sort of air buffer, that can be synced with the stroke movement).
I do suspect that some sort of fleshlight case mod can fix it, but no idea how and which fleshlights would work best here.
From my experience the boost sleeves seem to work best without requiring any modification. They have a sturdy front, and a more open chamber, and are designed for more suction to begin with, which for this system is optimal.
I havent used the nimblestroker myself, but i did hear that compared to a tremblr it has no chance of beating it, and this means it wont compete with a vacuglide either.
And its also worth to note, their comparison isnt entirely complete. It for example still says latex, even though for years the tremblr uses silicone by default. It doesnt mention stroke lenghts at all.
And it also doesnt mention suction strength anywhere, as if thats not relevant. And i can tell you from just its looks, its never going to beat a tremblr/vacuglide. There is just not enough room for any air chamber to enable strong suction. These milkers are large because they need such chamber for the power.
So yeah, i would never go for a nimblestroker. the vacuglide is significantly more superior here.