I have a bottle of "Gator's Grip" on order as well; it sounds quite promising, but I haven't tried it yet. I also can't comment on Gorilla "Wood Glue." I did use "original" Gorilla glue to build some cabinets in my workshop. It worked as advertised: it's strong, dries pretty quickly, and makes an unholy mess during application. All joints must be firmly clamped, as the adhesive expands in the form of a sticky, gloppy foam. Great for structural joints that need to be strong - and, preferably, won't be visible. Just about useless for model building. As I understand it, though, "Gorilla Wood Glue" is a completely different substance. One of these days I'll give it a shot.
CA, epoxy, and, for that matter, PVA haven't been around long enough for us to make any definitive pronouncements on their longevity or durability. I can, however, offer a couple of pieces of evidence on the basis of personal experience.
I have two ship models that I built quite a long time ago. I built my H.M.S. Bounty (extensively modified from the old Revell kit), between about 1976 and 1978 (if I remember right). Since then it's made four changes of residence covering three states (Ohio, Virginia, and North Carolina), which have subjected it to pretty significantly different climates. It's spent its entire life since completion inside a wood-and-plexiglas case.
My scratchbuilt Continental Frigate Hancock was, if I remember right, started in 1978 and finished in 1984. It also has endured four changes of residence (plus, before its masts were stepped, a round trip to England in a suitcase). It also has lived almost its entire existence (since being finished) inside a wood-and-plexiglas case.
I didn't pay particular attention to the adhesives I used in either of those projects; being young at the time I didn't care much about the lifespan of the models. (I'm older now, and slightly more interested in such things.) I did know enough to avoid anything containing lead (including lead-based solder), and I disdained balsa and pine. (I still do.) The materials in those two models include styrene (molded and strip- and sheet-stock), basswood, boxwood, cherry, pearwood, degama wood, holly, paper, brass, copper (including copper sheathing for the Bounty's hull), milliput, acrylic modeling paste, and probably a few more materials I've forgotten about. The adhesives included Revell tube-type plastic cement (would that it were still available), Testor's liquid plastic cement, Weld-on No. 3, CA adhesive (which was relatively new to the hobby market at that time), 5-minute epoxy, Squadron Green Putty, old-fashioned Weldwood contact cement (for the copper sheathing), Elmer's white glue, Titebond ("cream-colored") wood glue, and tin-silver solder. I think that's a fairly comprehensive list of materials that have now been tested for, in the Bounty's case, over 30 years, and slightly less in the Hancock's.
My report on how those adhesives have held up can be quite short: not one of them has failed or shown the slightest sign of weakening. I can't speak to the question of "brittleness;" those models scarcely ever get touched. (If they did, I'd be concerned that my 30-years-older fingers might brutalize them.)
Those models' excellent condition provides some other interesting evidence. The principal rigging material in them is silk thread. I've heard all sorts of stories of silk weakening over time, but every single line on those models is still in place. (Have I deliberately yanked on any of them to test it? No. On the other hand, the models have been subjected to quite a few car trips, and the bouncing around hasn't fazed them.) The paint I used for both of them was the then brand-new Poly-S. Lots of people have claimed that acrylic and latex paints don't hold up. I obviously can't state absolutely definitively that none of those colors has shifted, but they certainly look identical to the color photos I took years ago. And none of the plastic parts has shown any sign of warping.
Neither I nor anybody else can state with certainty whether the CA adhesive we apply today will still be stuck in a hundred years. But the evidence in front of my eyes suggests that it's pretty good, durable stuff. That doesn't mean something better won't come along. (I have high hopes for this new Gator's Grip stuff; I don't like CA for tiny photo-etched pieces any better than anybody else does.) But if the hobbyist's adhesive market doesn't get any better than it is now, it's pretty dang good.
All this should intensify our reverence for previous generations of model builders. The people who built those "Admiralty models" in the seventeenth and eighteenth centuries had no adhesive other than hide glue, and as recently as the 1950s people were making do with white glue, Ambroid cement, and solder. I have a great deal of admiration for those folks.