Re: "I'll put my money on a Skylon."
i doubt the x-37b is made from alloy, for the size of it, the rest would have to be 50% copper to last 3 years in space and being smashed by all the debris
you have NASA working on carbon plane frames along with spaceX, the main reason why you would have toughened graphite is the ease of being able to fix it with a quick space walk with polymer from a tube as the fibres have no specific order, which would also help if a nano tube force world would be used
if a shuttle was able to hover, with a jump jet system, then you can use the same system for entering atmosphere's and would'nt need ceramic heat sheids to handle the 6000c plasma build up
as far as the drive goes, you have 1 fixed magnet