See, while I've taken the opportunity to spool a VTX up to speeds in excess of R17 a couple of times, and considered it to be excellent fun, I'm not sure I see the point on typical BRITISH roads, where you're just going to get your teeth rattled and splashed with crud. On a race track, sure.
What recumbent trikes are really good at (assuming absolutely zero risk of BloodyTrains) is the tourer plodding, though I'm always amazed at how slowly I find myself riding barakta's Sprint when I'm not paying attention. Can't help feeling that (assuming you have the option) you're better off on two wheels. Or in a velomobile.
The Sprint X seems to be an acknowledgement of this inherent slowness, but by the time you've ditched the mudgards and front suspension and fitted some fast-rolling tyres you're half way to a VTX in terms of practicality.