@jviss
Since you mentioned Sparcraft, here is the history. Same building, pretty much same masts now with an in mast furling mast. Here we go on history.
Kenyon Isomat (friend of mine was their sales mgr.) located in Charlotte, NC was purchased by Z Spar (French owned company) with a facility near Alachua, Florida. The employees at both facilities were let go while the upper mgmt. (four people) for Z Spar in Florida were transferred to the facility in Charlotte. Without the proper training of new but lacking employees, Z Spar was behind in production and delivery of masts with boats built and delivered to dealers. I know as I had two boats for sale without masts. Eventually, the mgr. at Z Spar left for another job which many criticized but his hands were tied. Eventually, the name of Z Spar left out shores. The old employees of Kenyon Isomat reformed in the same building with the same masts but under Charleston Spar. As for Selden, they approached Hunter Marine and that relationship was born. Hunter made darn sure they would not go thru that again. Charleston Spar either was purchased or changed it's name to Sparcraft. I now note that Sparcraft is part of the Wichard group. As for parts for Z Spar, a new company, U.S. Spars opened up in the same facility that Z Spar once occupied outside of Alachua, Florida selling Z Spar parts under that new name and the ownership I have been told is by the same French company or Z Spar in Europe. Selden now supplies masts to Catalina and I am not sure about Beneteau as I have been retired for a while. As for parts for Kenyon Isomat and possibly Sparcraft, it is said that Rig Rite sells those part. I do not believe the forum store has any relationship with Sparcraft but not sure on that. I hope this helps all folks .
As for in mast furling from a dealer perspective now retired, companies mentioned do make excellent in mast furling but it is up to the individual choice what to purchase but the key here is what everyone has been saying, knowledge and experience to include learning is most important. The in mast was specifically designed for the leisure sailing, not for racing but as time goes by, things evolve. As for any information from me comes from knowing the folks who designed the original in mast furling which they asked my advice as well. I only report what worked for me. For example is the 1 degree or less for a straight mast when tuning note that with each boat the rake is different. Another when mainsail is jammed, I use to pull down on the sail by the mast and pull out at the end of the boom. Seemed to work.
I hope this information will answer some questions you have.