first off how big of a boat?
My dad and uncle had 2 put in like 30 years ago and I have never been impressed. 1) I believe they winches were undersized. 2) The supports for the boat was terrible. a nice cradle like the new lifts all have would be a lot better. 3) There is no real weight rating system like when lifts are manufactured. 4) How many of these has your builder done?
I know for a fact that the ramps my dad and uncle had done were done on the cheap. It may be worth it to spend better money on something like this.
Lake Vermilion has some really nice boathouses 10 feet from the water with nice ramp systems into them. I am not familiar with them so I cannot comment on that system. I would be very interested in that setup if it was built properly- drive the boat onto the trailer/ cart and hit the remote. That would be awesome.
Do you homework and ask if you can get some references. Can you see some that were done 5-10 years ago and what the owners like or dislike. Would they make any changes?
The positive would be no installation and removal fees for boat lifts. On Lake Vermilion they are like $200 a year.
Good luck
Steve