I decided that, as the only thing on the Inbred that wasn't black, the cranks had to be replaced, and they are considerably cheaper on eBay than from Hubjub (Will doesn't stock black ones anyway).
So...they turn up and at first glance they look the same as the old ones. Except they're black. But when I come to fit them it's apparent that the chainring - on the inside of the spider as before - is now going to hit the chainstay before I've even started to tighten the crankbolt. So I put the ring on the outside of the spider, the chainline is perfect and the fashionistas will no longer sneer at me.
There are, therefore, two types of Sugino XD floating around, and they are quite different castings.
