Hi Paul
The steering feel was fine with the 13" although of course physics suggest it should be easier with the 15" - yet to try it in anger as I only fitted the larger wheel last night.
Main reason was aesthetics - I'm not a great fan of wood wheels plus I'm redesigning the entire dash to make things quite minimalist (my winter project) . So as a first stage I've fitted a Mota Lita Classic 4 spoke with leather trim.
And I think MAdmax was looking for something considerably smaller.
Looking for a leather wheel myself , find that wood is a bit narrow !