I've also heard that if you have an old Bim200/Riba mast, all the latest sails will be a bit of a disappointment. Apart from the obvious hook vs ring, the slot is about 1mm smaller on the old Riba masts. Most importantly, however, is that the old Riba Masts are more flexible; therefore, new sails will be overly flat-- very bad for heavyweights like myself.

Now, if I change the Mast and Sail together, then a new Bim V1 starts looking more attractive.....