I do not think I ever seen anyone has floating dock system for 25 or larger boats in Northeast yet. (or may be I must look around more) Most of lifts around here are mechanical lift and they sit on 4 post. I have a 12000lb capacity 4 points (pilings) top mount lift for last 2 years and we really like the system based on:
-Can be installed on rough water (choppy) area
-Almost no maintainance (other than grease) is required
-We do not wary about Ice damage and leave as is during winter
-We do not have to wary too much on depth change.
Local permitting requrement might be apply depend on where you are but I feel it is the most reliable solution.
I would recommend to get a remote switch so you can make lift go up and down from your boat. Just load people on the boat and push a remote switch down and off she goes. When we return, drive boat head in and push a remote switch up. These lifts are made to go up and down constantly so I never use tie line to my slip anymore.

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