I've seen weapons done up more than that, by ordinary infanteers too, so it's not that uncommon, especially in theatre
Which can be a good thing or a bad thing, depending...
Contrary to what some might claim, sub-unit commanders have been turning a blind eye (even authorizing?) drop-in weapon modifications overseas. These include KAC Rails, ACOGs and Aimpoints, VLTOR buttstocks, ect. Some of these are more of a hassle than others to install, but none will leave any permanent changes to the weapon. The individual soldier could easily draw his weapon, modify it, then change it back and return it to stores exactly how it was issued to him.
Overall, I think the fact that this is becoming commonplace is a step in the right direction. But I've also seen these "unofficial sub-unit policies" manifest themselves in pretty retarded ways too. For the couple guys in my coy who were sporting ACOGs and Aimpoints, there was one who had a civvie pattern hunting scope on his rifle. For the handfull of guys who were wearing high quality chest rigs from reputable companies, there were also those who were wearing locally made rigs that were falling apart by the end of tour. The same went for slings (ref: POS locally made 1-points) and boots (and no-one will convince me that a zipper up the side of your boot is a good idea). As much as I think that letting troops take some initiative with drop-in weapons modifications is a good idea, I have to admit that it's a double edged sword. Some would be better off sticking with the issued gear.
I think the solution is not in standardization, but instead in education. Its great that non-issed gear is becoming more acceptable in Afghanistan, but if the guys can't train with their gear in Canada they won't have the experience to know whats good and what isn't. Really, all a guy can do today to make an informed purchase is read second-hand info from internet forums or have friends in the more open minded branches of the CF. Troops should be encouraged to take the initiative and experiment with gear while in Canada so they arn't wasting their money and risking their lives on POS gear in Afghanistan.