I carry a fixed blade every-day - I use IWB, which I find the overall handiest and easiest. No complicated rig to deal with, put on, take off, etc. Just thread the belt through it and go, and its pretty fast to access too. Carried openly ont he belt is faster, no shirt to get in the way, but I am a little un-comfortable doing that always. You can actually see a picture of the knife I carry on the Tactical Steel website,
http://www.tactical-steel.com/images/latest/atwood.gif - as you can see its one I made, prototype for a coming catalog model.
Also because of how the blade is to be used, edge-in reverse grip (AKA Pikal ["to rip", Visayan]) IWB works the best. An across the back rig would work too, but I get worried about falling (being knocked) down, and lading on that right across my spine and having it do damage, such as seperating my spine (I've read of it happening with SOB carry of handguns).
The sheath yous ee there is too wide, it should be folded across the spine of the knife, so it only needs rivets on one side, making it slimmer and easier to carry. DOne like the sheath for this blade:
http://conservationmilitia.org/Carbon_Warrior.jpg except with an IWB loop, not a static cord.
I do like the static cord idea though - the knife draws, taking the sheath with it till it hits the end of the cord, then it comes free of the sheath, keeping you from possibly cutting yourself. (Real handy if you have any extra padding around the middle).
I also like horizontal along the belt carry, under an un-tucked shirt, it works very good, and conceals well with a smaller sized knife.
Of course there is also neck carry, which is one of my other EDC methods of carrying a fixed blade - in this case a La Griffe. The chain may look kind of weird, but you could always do like the designer of the HideAway knives is doing, and have a necklace disguised chain, go to
www.hideawayknife.com to see what I am talking about.
I like shoulder rigs - my ideal one has my main fighter (something sort of Randal Model 1-ish) under my strong side arm in a break-front sheath, for a fast straight to target draw, that I can do without reaching across my body (telegraphing my strike before my blade is even out) - and then has an A/F dagger under my left arm for a break-front weak side or cross draw strong side back-up draw. The importance of having that main knife where I can draw it without reaching across my body and telegraphing is crucial, at least to my way of thinking. If at all possible I dont want the bad guy to have the foggiest idea until he feels cold steel in his belly - failing that, I want to be able to at least start my draw before he realizes what I am doing - and if pushed from un-armed to blade, I want it to be as fast a draw and as fast to target as possible.
Then again thats important for me all around - easy and fast.