I read on article about these dies just yesterday. They are a custom order job from Hornady and according to the article I read fire forming is still necessary to sharpen up the corner on the shoulder. The theory is that you can do load development for your cartridge from the very first firing instead of "wasting" barrel life fireforming the cases to your chamber.
I think it would be a great idea for cartridges that are very different from the parent cartridge, but if your Ackley is set up correctly you should be able to shoot standard 243 loads and get perfectly formed cartridges while still having an effective round.
I've only dealt with one wildcat so my experience is extremely limited, but we were firing test loads out of the parent cartridge, and the powders that shot the best with the parent cartridge also shot the best with the improved cartridge so we didn't feel like we wasted barrel life fireforming the brass.
far as I'm concerned, hydraulically actuated anything, especially portable things are great. The best thing I ever bought was a hydraulically actuated, portable, hand held geat and sprocket puller. best puller I ever bought.