I like my CDI
THere is no 'best' roller furler.  It really depends on what you want it to do for you. Do you race or cruise?   I have found the CDI ff4 to be excellent on my C25.  It does not have some of the adjustability of some of the other units, but that is nothing I miss on a boat I use principly for cruising.  If you are looking to do serious racing, a more sophisticated unit might be better for you.  It will cost you considerably more, however.  As far as the question about buying elsewhere and then asking a local shop to do installation, I would check with the loft you want to work with first.  Some of our local shops would do what you want. Others would insist on providing the materials.Justin - O'day Owner's Web