I’m considering buying a mast from OceanSportsAustralia and using it with an adaptor to fit my existing Duotone foils.
I was wondering whether using an adaptor affects performance in any way. For example, does it make the setup less stiff? Or are there other aspects I should be aware of?
Obviously, it will depend a lot on the quality of the adaptor, but I’d love to hear from anyone who has used an adaptor and what their experience has been.

My oneoceansports mast and code adapter is rock solid, I recently upgraded to a titanium one.

The SS is a great mast, especially with bigger spanny foils of 1300-1600cm2 its stiffer as most.
Duotone has a saddle type of mastconnection. I have the same with AFS and you can get adapters from that from Jim Stringfellow.
The positive is that the connection is stiff, the downside is that it is notticeable more draggy compared to the AFS UHM80 without the block of aloy inbetween the mast and fuse.
I can,t say for 100% sure its the adapter, but with the same fuse and foil and both masts have aprox the same diameter and overall cord it seems to be the most logical conclussion to blame the extra thickness arouund the head caused by the adapter. Because I really liked the extra stifness of the OO mast
I asked Stringfellow to make me a custom fuse: axis/one ocean head to AFS foils but unfortunally he stopped making custom fuses for now.
Bit of a pitty because with the adapter the excellent OO SS mast is not gonna be used so serious considdering switching to a foil brand like Code (S2) where the adapter falls into the fuse or switch brand of DW/supfoil foils including mast.
I demoed the Naish Excalibur and really really liked that one for its insane low end.

It’s not the salt water it’s the fact that carbon and aluminium are about as far apart on the galvanic table as u can get. They should never ever touch. So foils designed for ally masts had some glass at the junction. Just a bit.
full carbon systems may or may not so you’re taking a risk with an adapter. Not a big issue as it’s only touching when in use, I’d just be religious with disassembling and inspection of all fittings, even ones elsewhere on the board. EG I’ve seen a stick on shark repellent system cause full thickness corrosion in fin bolts on longboards