What makes you think it's Russian? A running trap is good no-moving parts and reliable, but you may get a smell from any residue between the shower and the running trap.
A waterless trap should work well as long as it lasts, which could be 5 years or even 10 (the HepVo valves, which work on a similar principle are claimed to have a life expectancy similar to that of conventional water traps), but, as you have identified, anything with moving parts, especially bending ones, will have the risk of wearing out. I'd be inclined to fit a running trap only if the membrane proves problematic. FWIW, I've twice had to use a HepVo on a shower installation and not had any call backs on either.
I wouldn't go about repairing that trap unless Lunns agress to it - if it causes a problem, it'd be your responsibility.