In reply to CallumKX: I went through Muiras, then at the moment have a pair of both Pythons and Cobras. There doesn't seem to be much in it for performance, except that the Cobra is so streamlined, and maybe has a slight advantage smearing. However for me the fit of the Cobra is better than any other boot I've come across, but I suspect this is morpho. Going 2.5 sizes down from my training shoe size gives a well filled toe box. The big up for me with these shoes is that I don't get an inflamed or sore Achilles from aggressive sizing.
Consequently, I'm buying up pairs from
http://www.telemark-pyrenees.com/en/lasportivacobra-p-522.html
Currently selling at 59 Euros
As soon as you've nailed your size in Sportiva, they seem reasonably consistent across Cobra/Python/Muira/Testarossa