Ghost E-Riot w/625 battery at 4,124 Euros is probably not smart system - so you do not have option of range extender. Also looks like it has "old purion' if that matters etc. Great value however.
The Rails look 'dated' these days and I think locking and removing the battery seems out of place on the trails. But there are many of us who need to remove the battery on a regular basis . . .
CSU is crown steerer unit -the upper part of a fork, that on Trek Rail is oversized to match the oversized head tube. A normal fork (without the oversized csu) looks weird, even weak compared to stock.
I think you said you work at a Trek shop, so I have a question - are CSUs' available for fork upgrades? Fox, SRAM maybe? (looks are important, but I bet it is stronger too?)
I think too steep seat angle can diminish pedaling/comfort. Try shifting weight forward or better yet, drop saddle and sit on 'whale tail' part of saddle for the tech climbs - yes counter intuitive I know.
In a mixed group, the beauty of emtb is you can ride at the 'group pace' and even exercise/suffer if you want to! And yes, no need to debate the old school guys etc.