One of the reasons I'm a fan of ITS, is that it shakes up the meta and requires you to do more, than just bring the net list in season. Another reasons is how the format allows to tweak the rules without risking to bring down the basic system – like upping the damage of TAG weapons etc. However I rarely see a tournament, that makes extended use of the optional rules. The Spec Op is rarely in use, and I'm yet to see a tournament, that allowed the hiring of Mercs in normal armies. And I mean, what is the worst, that could happen; PanO getting access to Smoke+MSV2 just like everyone else? Paying 1SWC for a common trick is a steep price. So what is your approach to these rules? Are you in favor, or do you want to play 'by the book'?
Your title is a little misleading. Are you asking about ITS Extras like Specops, Limited Insertion, Soldiers of Fortune, etc...? I have answered that yeah, almost every monthly tournament has an extra where I live. Or are you talking about the rules in the corebook like terrain, vehicles' catapults, narrow gates...? Those I only see when they are part of an ITS scenario, like the "blow the antennas", or when they are part of the online campaign like Wotan and its take on 0g.
My meta used to always use spec-ops. Once we all figured out that a super specialist was simply the best way to go - we stopped. It stopped being something creative and fun and became a staple. something you AND your opponent both had. it mitigated the weaknesses or strengths of some factions. I think more people are afraid of soldiers of fortune than have actually played with it. I could see how the fear of it ruining an entire tournament is enough to simply keep it out.
Its posted under ITS, so you answered correctly ;) Because everyone and their mothers know that, duh! ;) Same story here, the specops fell out of favor – personally I was a fan of the 0 SWC mimetic multi-sniper hacker, that gave me access to 8pt REMs. Although, I don't see the point in being 'scared' of something, that will just go away in a season.
I think in general the various ITS extras are fun, I see Limited Insertion used most often. I dislike spec ops, personally, as they let you custom build a model specifically to take away from traditional shortcomings in a faction/sectorial. I'm not a fan of things that homogenize the factions.