Of course it's different ... those silly Russians carve bullets out of potatoes.Nah, but if you give a LMG to a Grenadier who was trained to use it and a farmer, teacher, shoemaker etc. who happens to be a partisan... who do you think will handle it better? It makes sense to me.
On topic: I used CEs pretty much for repairs only. With 10 less mp cost you can also get them some seconds faster to repair that IS-2 or whatever vehicle that´s in a doctrine without conscript- or self-repairs. We are talking about minimal changes here anyway.