@martin: I don't blame you, but PuTTY is pretty slow for new releases (0.64 came two years after 0.63, and that one two years after 0.62, possible 0.65 might be soon-ish with the ECDSA though I guess), though worth noting by all intents even 0.64 despite being the latest "stable" release is still technically a beta :P
But yeah it'd be cool to see some support for it if possible, so far I've had no issues with them in PuTTY alone across multiple distros so at the very least puttygen is creating the general details properly, I'd assume getting the .ppk it generates working in WinSCP wouldn't be too horrible?