Nice review of the platform Eric. I have had this rifle on my must-have list for 2+ years and I will get one as soon as my honey-do list is completed to her satisfaction.
The rifle is also sold by Umarex in the USA in a plastic stock with a fitted silencer as the "Fusion", Pyramid Air's BB Peltier has a 4-part Blog on it that is quite informative as well.
In addition, MM at Flying Dragon has posted on the GTA quite a bit about the XS60 itself. It seems that any of the problems associated with the end cap leaks are easily remedied. I'm not 100% certain, but if I read all the posts/blogs correctly, between the lines, the end cap is not always assembled correctly from the factory. In particular, the piercing end needs to be tightened onto the body completely, otherwise the big O ring won't be deep enough into the tube at the point the CO2 cartridge is pierced, and that causes leaks. Also, the O-ring itself (as Eric noted) is squishy and swells - these need replacement with the right material, EPDM for example which is an easy fix. The trigger is adjustable, but you need to do some filing of the safety tab to make the adjustment - this from MM.
Cant wait to get one (of course I will wait, but....)