Jane, during our restoration of our WS42 Ketch, Harmony, we replaced all standing and running rigging. Included in that list was the roller furler on the headsail. Harmony had an old Harken unit that was unworkable. Having had great experience with a Schaefer roller fuller on our last boat, I installed a Schaefer unit on Harmony.
We went with a big 4100? unit based on Schaefer's recommendation. We have used it for the last 3 years and have found it to be fabulous. By the way, the folks at Schaefer spent hours on the phone with me giving counsel and recommendations.
Each year when we haul out for the winter, we have the fuller checked by a rigger familiar with the units.
Anyway, that my couple of cents. I have used a lot of Schaefer gear and have found the quality of finish and the longevity to be superb.
Doug
PS - I wanted to install a roller furler for the staysail, but the cost was too much at the time (~ $4000 excluding the cost of recutting the sail). Moreover, I wanted to see how the staysail worked on the boom first.