Hi Duncan,
The Tacktick Micro compass is generally favoured, certainly in the UK.
However, other compasses are permitted and the standard RS Aero compass mount has a flat surface which you could easily mount another flat backed type of compass on.
In case of single display compasses with displays facing backwards are used the Class Rules were relaxed recently to allow the compass to be mounted anywhere on the centreline between the mast and vang cleat, so they could be moved forwards to be more viewable.
The
Class Rules C.5.1 (a) & (K) describe how compasses and their mounts can be attached to the RS Aero.
I hope this helps.
