The only common thing between these cameras is that they accept the same lenses
SRT: fully mechanical, meter is quirky (clc) and needs mercury cell (or workaround), dim viewfinder, feels rather massive
XD: electronically (and very sophisticated) with emergency mechanical speed, standard batteries, bright viewfinder (acu matte)

If you do not have an aversion against electronics and are able to switch to "manual" if you need it I would clearly get the XD.