All, very many thanks for the warm welcome and this well-thought-out advice.
Definitely helps to persuade me I'm thinking in the right direction... just wish St Croix had been able to sort out a sustainable UK dealership which might make it easier to try before buying, rather than import sight unseen via the auction site or similar.
Naturally, if anyone else has any more insights, I'll drop in periodically to find out (luckily it's still some time till trout season starts again). This feels like a friendly, well-informed site where I could feel quite at home
Thanks again all!