I agree. I bought a boat with teak decks and love them and am having them updated. But when they get beyond that and am told to replace them, I will put some kind of grip decks on the boat. Teak is easy to maintain in salt water, just get them wet and use a not too stiff brush to keep them clean. But so are nonskid decks.I can't speak to the installation question in any detail, but I would mainly like to comment on the resale issue that you raised near the end..
My only comment on the installation issue is that the preparation for some of these systems is actually more demanding than the prep for paint.
To explain. Some of the faux teak decks are self-adhering. And those require perfect preparation in order for the thin layer of adhesive to properly bond to the deck below, and also not telegraph any irregularities.
Other systems, use a trowel or roll on adhesive with gap bridging properties. While harder to apply those systems can escape some of the prep issues that come with the self adhering systems.
The preferences for a teak deck or not seems to be a regional thing and a very personal preference thing. The European marketplace seems to have a much stronger preference for teak decks, or faux teak decks than North America and perhaps the rest of the world.
For example. Beneteau told me that they just about can't sell teaked decked models in North America and even minimize the teak from the cockpit of boats intended to be sold in North American vs. a large percentage of the boats sold in the EU opt for teak decks. The same is true for J-boats.
So in terms of resale, I would suggest that adding the faux teak decks should be seen through a lens based on where you plan to sell the boat as well as your own preferences.
Regarding Kiwigrip. I did homework on using Kiwigrip for my own boat. I think that it is a good product and looks good when it is applied carefully. ( I will note that my boat had decks that still had molded in non-skid, and which had been painted previously painted. So this may not fully apply to your case.)
I ended up painting my decks with a conventional paint because the boats I had seen with Kiwigrip looked a little more amateurish than boats with non-skid paint jobs.
In terms of resale my feeling is that Kiwigrip makes sense on older less valuable boats where nothing will raise the sales price above a low threshold. But, my sense is that Kiwigrip potentially diminishes the value of a bigger more expensive boat.
If you are in a marketplace where teak decks are valued, my sense is that the more expensive custom plank layout will add to something to resale value, but even if it doesn't add the full cost difference, it would make the faux teak more appealing to a larger group of buyers so potentially the boat might sell more quickly.