Compared to 2nd hand Macs, the X1000 is a even more a dead end: it'll be produced in small quantities (tiny compared to the Macs) and the amount of spare parts / boards will quickly run out after the production is finished. 5 years after last PPC machines were produced by Apple they're still easy to get. 4 years after bPlan ceased producing Pegasos 2 boards they are very hard to get now (although still repairable!) - and nobody will make me believe that A-Eon will sell more boards than bPlan did at the ridiculous price. Therefore 5 years from now, the PPC Macs will still be on the market, while X1000 will be very hard to come by IMHO (assuming they'll enter end-user production at all or won't have hardware issues that'd make the boards unusable 5 years from now - hard to judge the quality if no end-user boards are available).
