In reply to Sealwife:
They tend to stretch a lot, I've had a pair for the last two weeks, worn about 4 times and they now fit nicely. Havent previously had the spirits I know that red chilli tend to stretch a lot so went for a size and a half down from my street shoe, pretty painful to begin with but they stretch so much they fit like a glove now.
Other than that the rubber does tend to wear down quite quick, but assuming you bought them for 40 quid on rock and run like I did then I wouldnt be too concerned about lifespan.
I have a pair of RC spirit lace ups, they stretched nicely. My corona velcro however have never stretched and i can only keep them on fo short periods of time. I had them 2years before I gave up and bought the spirits, now I only keep them for the really tough routes- they are great shoes!