Well, seeing as almost no one at VAF has a full harness, the point is unfortunately moot. People learn the techniques of harnisfechten, but by and large we're a blossfechten group that happens to do a little bit of armored fight. I wish more people could afford quality armor so we could do more armored stuff, but that's just life.
If more people did have harness, I'd happily have us do "what if" scenarios with them, but full out free play like that would be very dangerous. If I have armor and my opponent doesn't, I'd close in and use my armor to it's best advantage... and against a friendly partner, there'd be a very high chance of me injuring him with all of the metal parts of my kit, particularly falling on top of him to pin him.
Something that bothers me is that the training, no matter who is doing it, seems to be either unarmoured vs same or armoured vs same as well as same vs same for weapons (thought I am trying to counter that in the local SCA group & the Kingdom as a whole eventually).
I can't speak for SCA, but I can say that a lot of what *we* train comes from the context of a judicial duel where it was illegal in most cases to have mismatched weapons. That doesn't mean we don't mix it up sometimes with different weapons, but it isn't where our focus is.
"Professionals are predicatable, unfortunately the world is full of Amateurs."
How does VAF train to defeat the guy what does a thing cause he knows not to not do it and/or he will be perfectly happy with a Phyrric Victory?
We don't train for the guy who does something different; We train to win. Period. If you train specifically for the wild card, you miss the forrest for the trees. If you train to win, then you encompass everything. But again, that has nothing to do with our armored program, because we don't get the opportunity to do serious training in that for practical reasons.