Immediately noticeable about the Pioneers is how tall they are. They taper down towards the base, to give extra heel clearance.
Build quality is very good and there're loads of features: reflectors and LED light clip, a padded base, external pockets and a zippered top pocket that stows a bright orange cape. The R and K mounting system is well made - there's a stabilising clip and the top hooks ratchet in for a secure fit (up to 10mm rack tube diameter) and are very easy to use. However, there's limited lateral adjustability at the top - about 4cm for each clip. The back panel is weather proof, stiffened with plywood and the front and sides are durable but not waterproof.