Close enough. It's just the cap and bolt, and uses the existing star nut or compression plug.
Pitlock skewers replace QR ones just fine. Braking system has nothing to do with it.
The Pitlocks for disc brakes are to replace the caliper bolts that hold the caliper to the frame.
Thanks for the responses everyone. I went and ordered the entire kit since I am planning on upgrading to some nice disk brakes within the next 18 months anyway (within £100 budget anyway...still 3x the value and effectiveness if reviews for current braking system are anything to go by). The kit I got which included the ahead lock, 2 disk brake locks, 2 wheel skewers and the saddle stem was the best value rather than getting individual skewers. Also means I only need to have one pitlock key for the entire setup.
Maybe I'm reading it wrong, but I was once looking up prices for a moderate upgrade just to see how the parts break down and I think it was like £48 for the Avid BB7 calipers and £60 for the entire BB7 kit so securing nearly 5/6 of the value using the pitlocks is good enough for me.
I understand about the handlebar risk but that costs about far less than the stem. I guess I can use some tape to make the bars look a bit more beat up or something.
If I can find good quality security/obscure screws which match the quality of those on the Thomson Elite Stem, I suppose I can replace the ones securing the handlebars at some point in the future. Worst case, I'll go down the candle wax/ball bearing/solder route for securing it. Same goes for properly securing the saddle at some point rather than just the saddle post.