I've found the POR-15 -when applied strictly by the book- to be very good and solid paint.
I especially like the tip they gave me to lightly dust the still tacky POR-15 coat with spraycan-primer, this way it really adheres well together and you won't have to sand into the POR-15 itself. Just don't fully coat the POR-15 as you will get cracks in the primer!
I use it whenever I don't see the need to replace structural or body panels just because they've corroded a bit, just thoroughly clean them from paint and other foreign materials and use the Marine clean liberally (preferably mixed 1:2 with hot water), apply with a scotchbrite or something, use the high pressure cleaner to rinse well, then spray on the metal ready and use a brush to make it really penetrate all cavities as it leaves a zinc-phospate residue that the paint really likes to adhere to.
Make sure you get small bubbles when brushing. Without proper metal ready prep the paint won't last. Been there done that!
Just be sure to rinse again after the metal ready but leave it for a while (30 min) and make sure to spray some water mist on the metal ready'd panels to amplify the effect.
Don't paint unless you're sure the surface is bone-dry! Will be pretty fast in your climate but compressed air (moisture trap!) will speed things up.
It dries in about 2 hours so spray the dust coat of primer on fast if you want to topcoat.
Have faith in the paint, it works pretty good.
The Tie-coat primer goes on without abrading the POR-surface because of its' special compound however but I feel it's best sprayed on as it doesn't cover very well.
Best of luck to you!