Anyone have any experience with Next Level finish? If so, how does it compare to Gen 4?

It's thicker which I like. I do mostly saltwater rods so I can get a single coat where I would have to use two coats with about anything else.

I’ve been using both. As mentioned it has a thicker viscosity so it should be warmed a bit to help it apply and flow out well.

Working time has been sufficient for me to apply to a good section of decorative wraps and also coat a full guide train of double-foot guides.

It flows out very nicely and due its thickness may allow a coat or two less on decorative wraps. I still end up applying 3 coats on guides as I like to apply a very thin first coat, a second for coverage and a third to tidy up those little area at the peak of the guide foot that sometimes need a little more etc.