Go with the Lectra/San..for several reasons
The PuraSan is only certified for use with 3 toilets, all Raritan: Crown, Crown II, Atlantes. So unless your toilet is one of those, it won't be legal.But even if you do, the PuraSan doesn't use chlorine tablets. The chlorine is supplied by a cartridge containing a single "tablet"...the flush water goes through the cartridge that has to be mounted above the toilet. A cartridge lasts about a s season, maybe two, depending on much the boat is used. Replacement cartridges for the PuraSan are a whopping $80 plus HAZMAT shipping. Due to HAZMAT shipping, few if any dealers carry it...so you'd have to order it directly from Raritan, which could be very inconvenient from the Bahamas.Salt, otoh, is cheap and readily available everywhere. You can either install an optional salt tank, or just add 2 tablespoons (one coffee measure) of table salt manually to each flush. I'd recommend installing a tank too...just a small one--10-12 gallons...you'll have to use it in the Keys, and you could drop into a small no-discharge harbor or marina along the way.