I was in the boat lift business for over 10 years. Best bet is to call the manufacturer and they will send you the specs that they normally send to trailer manufacturers. Short of that the best advice has already been given, make sure you support the transom or the boat will develop a hook. Reggie told me about 13 years ago "I hate you guys, after a customer stores a boat on a lift they call me the following year complaining that the boat has lost speed." Ever since then I always called the manufacturer.
If you got the $$$ go for the Myco setup.