Heck yes, Brightside all the way. I've heard good things about Kiwi Grip, which is a combination of paint and stucco-like nonskid, but have no reason to abandon what already exceeded my expectations.
Now towards the end of that 15 years it's true, where the finish has not been renewed does not look new - it's a bit chalky and chipped here and there. But it still looks fine.
Got another question from a PM, would prefer to have the discussion where anybody can see it.
Sanding: with "grid"-patterened nonskid, there are a couple of interesting yins and yangs:
* yin: you can't get sandpaper in the grid valleys
* yang: the grid valleys don't experience much abrasion in use, so the paint doesn't wear much even if the underlying preparation isn't perfect
* yin: when you sand the grid, only the peaks get touched with the sandpaper
* yang: the peaks are what contact your shoes in use, so they're what needs to be best-prepped for paint
* yin: repeatedly sanding the peaks and putting paint in the valleys reduces the degree of nonskid "relief," and reduces the grab of the nonskid
* yang: after two rounds of painting and many years, you're going to need to add an abrasive to the paint. A smoother surface on which to put the abrasive-laden paint is preferable, so less "relief" is fine
The lack of contact between the valleys and the sandpaper is why being aggressive with the Chore Boy pad when cleaning makes sense. Hit 'em hard with what will hit 'em: SoftScrub with bleach, and copper Chore Boys. Bronze wool is even better but very hard to find.
My tools for sanding are a Makita disk sander (a versatile tool infinitely preferable to the palm sander which uses rectangular pieces of sandpaper), 120 grit extended-use paper, and a $30 face dustmask. Deck fiberglass turns out to be surprisingly soft, so I don't press too hard with the sander - just a little more pressure than the simple weight of the sander. In practice it's easy to see when you've hit the point of diminishing returns.
In terms of deck hardware removal, I suggest removing stanchions as they're simple to access and their bases cover a large area. You can certainly mask around any other stuff you don't want to remove, that's a trivial process. But having discovered the simplicity and effectiveness of butyl tape (search the forum for this too), epoxy "plugs" to seal the core around holes that penetrate the deck, and slightly-countersunk deck holes to enhance the sealant effect, I have never regretted taking something off the deck to more thoroughly rebed it.
Masking: regular blue painter's tape. Yep, it's a pain to tape around the curves and corners.
Paint application: small roller and brush. Brightside is very forgiving. A quart of their Special Thinner #216 is also useful.
Primer application: buy a tube of tint and tint the primer to a first-order approximation by eye, it is not rocket science and makes the paint cover much more quickly and easily. (I learned this trick from a blind guy, believe it or not.)
Abrasive application: I use a saltshaker on top of the first coat of wet paint. You can do it that way or you can mix the abrasive into the second coat. I suggest erring on the side of "more abrasive."