I say lifeseal, lifecaulk or 4200 only, that's what it's designed for. the 5200 is more of a permanent bond and next to near impossible to get apart unless you buy the release agent.
LifeSeal:
http://www.jamestowndistributors.com/userportal/show_product.do?pid=1536
BoatLIFE LifeSeal Polyurethane/Silicone Sealant is a one part, fast curing, low odor, high adhesion, non-sag compound. LifeSeal is excellent for sealing decks to hulls, underwater thru hull fittings, vinyl ports, windshield setting glaze and the bedding of marine hardware. It retains excellent adhesion and elasticity under all weather conditions.
LifeCaulk:
http://www.jamestowndistributors.co...t.do?pid=2770&familyName=Boatlife+Life-Caulk+
BoatLife Life-Caulk is a long lasting, permanently flexible marine polysulfide sealant which can be sanded, painted and used above and below the waterline. Tack-free in 1 to 3 days, Cures in 7-10 days (weather dependent). Excellent resistance to teak oils, gasoline and diesel fuel.
4200:
http://www.jamestowndistributors.com/userportal/show_product.do?pid=2004
4200 Fast Cure is a one-part general purpose Polyurethane selant with a good adhesion to wood, fiberglass, gelcoat, plastics and metals. Forms watertight, weather-resistant seals on joints and boat hardware above or below the waterline.
3m 4200 fast cure is ideal for hardware and bedding applications. Paintable and sandable. This product is approx. half the strength of 3M Marine Adhesive/Sealant 5200, which allows for disassembly of parts.
Your three choices are; Polyurethane/Silicone blend, Polysulfide or Polyurethane. 4200 is the strongest, followed by lifeseal, then lifecaulk. They all have their places depending on the application.