re: O'Day 23 Roller/Furler
I installed a CDI on my O'Day 222 last summer and am very pleased with both the ease of installation and performance under both light air and winds up to 25 MPH.
I researched every brand available and settled on the CDI as the best cost/performance choice on the market.
I spoke with an outfitter who made me aware of the danger of the sail and furler not matching up well, so I ultimately ordered a "package" from Sail Warehouse in California. The package approach took a lot of guesswork (and time) out of the installation. Installation took about two hours, did not require dropping the mast, and was relatively simple.