I don't have personal experience, Skip, because I dry-sailed my boat (kept it on the trailer, mast-up) this season, the first season I've had my used CDI, so I only raised and lowered the mast 4 times. But these dealers:

both specialize in trailerable boats, Don formerly in Seaward and now in Hunter, and Rob formerly in Potter and now in Com-Pac, and both swear by the CDI furler for people who raise and lower their masts each time they sail. Don was the guy who sold me my used CDI off a totaled Hunter. To my knowledge, neither dealer sells the CDI, they just know what has worked well for their customers. I know that if you write to Rob Voigt, robvoigt@GLSailboatCo.com , and mention my name and your interest in the CDI for a Montgomery 17', he'll happily share his opinion. --Craig

p.s. I'm not necessarily trying to convince you that the CDI is the best product, I'm just trying to hook you up with some useful information. However, I could be wrong, but I think the CDI is the leader in over-the-forestay-foil furlers for trailer sailors who frequently raise and lower their masts. You might find some opinions and information at http://www.trailersailors.com/