TheMeanGreen- Welcome to Autopia!
I have extensive experience with both KSG and FK1000P. For almost all applications I've quit using KSG in favor of the FK1000P.
The benefits of KSG aren't significant IME unless you apply at least four layers (and I consider six or ecven more to be much better). Fewer than three layers and it won't last much, if any, longer than a lot of other products. At four layers it achieves the best look it'll get (and it's a bit of a signature look that some don't like on some paints, same goes for the FK1000P as well). Six layers lasts a good long time and allows you to easily "clay the KSG clean" without the clay stripping it (at least if you do the claying properly
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With FK1000P you can do one coat, wait until the next wash and do another, and maybe repeat that again after a while and it will IME equal the durability of the many (more) coats of KSG. Then just add another coat whenever you think you oughta, or when you have the inclination.
Both protect fine against bugs/bird bombs. Both wash clean easily, but the FK1000P is superior in this regard especially over time.
One unique feature of KSG is that if you layer it quite heavily (which I'd always do if using it at all, can't overemphasize that!) it will end up with a significant "build film" on the vehicle, a truly protective physical barrier that IME is unique among waxes and sealant.
With the conditions you described, *any* product short of a coating might be hard-pressed to last 5 months, but IMO you did chose the right two to pick between. I'd do the FK1000P if only because you don't need to layer it as heavily.
These days I only use KSG on exterior smooth/shiny black plastic and other exterior plastic/rubber/etc. trim; I use it for that "protective barrier"-effect. I no longer use it on paint or wheels although I did for many years.
And FWIW I find KAIO by itself to be very short-lived so if at all possible I'd get a coat of KSG on top of it right away.
FWIW#2 I find that KAIO can *NOT* strip polishing oils left by products like M205. I've always done a thorough stripping of polishing oils before using the Klasse twins.
FK1000p bonds to various things quite well. People here have used it over glazes with no problems and I use it over polishes that leave some protection behind (e.g., 1Z Pro-Line Metallic Polish) and also over various All-in-One products (e.g., both KAIO and ZAIO).
If working by hand, I myself would probably go with a combo like Zaino AIO topped with FK1000P.
Both KSG and FK1000P should be applied *VERY* thin...one ounce of KSG is more than I'd use on a Suburban. If you use too much both can be a PIA to buff off, with the KSG being the harder of the two. That said, I myself find both easy to use (thin application, let dry until passes the "finger-swipe" test, fog with your breath, buff off with plush MF). If you apply KSG to exterior trim, use the wipe-on-wipe-off method instead of letting it dry (I've used FK1000P on trim but don't advise that others try it..do *NOT* let that stuff dry on trim).
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