Let me give a bit of insight because I went through what you're doing about 2 months ago.
Hard backplates look uncomfortable. The strap system looks like a pain in the ass. Those big screws with the wing nuts sticking out in the middle of the backplate holding the wing/single tank adapter look like they're going to stab you in the back. It's amazing how deceptive appearances here can be. After getting a bp/w and diving with it, I'm shocked how much more comfortable I find it than a normal BC. It just goes away like it isn't there. I thought long and hard about going with a softpack option like what you're looking at (I was mainly looking at the HOG system). I am glad I didn't. No need for it whatsoever.
Yes, all 3 companies you listed have hard backplate options. Frankly, there isn't a whole lot of difference between the different brands. Some quality/workmanship in the wings. From there, it's little things like is the inflator hose on the wing center mounted or off to a side, does the wing have a built in single tank adapter, etc.
I, personally, ended up with a Hollis system because that's what my LDS carried and I got a great price on it. I don't have an intention of going DIR with it, but I do have my set up configured somewhat like the DIR configuration because stuff like the d ring placement and the crotch strap work quite well. I wouldn't shy away from something DIRish simply because it seems like it's too tech heavy. Likewise, I wouldn't do something purely DIR just cause. I have the Hollis Elite II harness on mine, which is adjustable and has quick releases, but I only have one d ring on each chest strap. You'll find what works for you. That's the benefit of going this route. You get to adjust it to what is right for you and your diving.
