This is certainly the case for me. I primarily use my 4 wood as a mini driver on holes where a driver will put me in trouble. The 4H, meanwhile, is a great fairway club (and rough club). Of course, YMMV.
To my knowledge there's no such thing as the JPX 825 Forged. The 825 Pros are forged, but they're just known as the 825 Pros (as opposed to the EZ Forged; no idea why Mizuno went that way with the EZs).
Per the link the silver crown SLDR is (or at least was a year ago) a tour-only version, which certainly would make sense in light of what else you've told us.
While the online fitting chart is a great starting point it's by no means a substitute for a dynamic fitting. At the very least you'll want to go to a store and hit balls off of a lie board with lie tape on the sole of the iron. And you can do that for free. Sure, it'll take a little bit of time, but it will be well worth it. Of course, a full-on fitting would be even better but that usually costs something.....
I love my Four5. The only downside to it for me is that there's more club chatter because the clubs are separated. I've heard that people who use midsize or oversize grips have more problems getting their clubs in and out of the bag; but I have small hands with standard size grips so that's not an issue for me.
While I've only had it a short time, I absolutely love my Four 5. The padding on the shoulder straps is insanely comfortable. The 14-way divided slots work great for me; they've even reminded me that I left a wedge next to the green.