Boat lift (elevator/4-piling) suggestions or feedback?

[msavold]

Folks:

Can I get some feedback on an elevator vs 4-piling lift based on your experience (and not that of the 'Brand X' salesman: of course, what he is proposing is the best and all other brands are crap!)?

Background:

1. We're near the ocean on a canal in brackish water. Salt is in the air and seems to attack everything!
2. We have an existing dock that we would either like to keep (elevator option) or reduce in size (4-piling).
3. The community limits us to 13' out from the bulkhead so putting the 4 piling beside the existing dock is not an option. Floating docks and covered docks of any kind are not permitted.
4. Canal bottom is muck with sand underneath, God knows how far down. Depth at the dock is about 24 to 34" at low tide. Good but not great. Move out about 4' and it increases to about 42"-48"

4-piling guy says elevators bind, get 'out of square' easily and can continue to sink into the mud/sand. Undisputed fact: they cost more. Elevator guys say if installed properly there's "no problem", can dock easily from either side without having to thread between neighbor's boat and outside pilings. (I'm thinking something in the 6,000 to 7,500 lb range would be more than enough for a 240.)

And then there's the flat plate / sealed drive question... Leaning toward flat plate since a LOT cheaper...