I'm sure you'll be able to make it work somehow (as they say in the car world "with a welder, a torch and enough money....") but looking at the backside the hipbelt is made to mate to 2" webbing (with some wiggle room, we'll say 3" just to be safe) and the shoulder channels are made to go over regular width shoulder straps. My guess is that the HPG stuff will fit, but you will have to roll/fold them to stuff them through. At that point the HPG will be making very little contact with your body and my guess (without having used the ALIPAD) is that your body won't be able to tell if there is a high quality suspension system or a leather strap on the other side of the ALIPAD.
I know the HPG stuff is comfy, I'm assuming the ALIPAD is comfy, but both together seem redundant. A question I would ask is would the ALIPAD improve the Ute? The Umlindi? If so why, if not, why the ALICE?
the problem I kept running into when I tried to mate different belts to the ALICE is they always seemed to slide or pivot around too much to transfer the weight well, that might not be an issue for you though. Also I had trouble getting the "delta straps" (or whatever you call the webbing the sucks the pack to the waistbelt at the sides) to mate well, I'd love to see how you solved that, have any pics of the side of the belt/frame?
this isn't me trying to be smarter then anyone, I just believe in aggressively pursuing the best options. I'm new around this forum but I know that for me personally I prefer to start a dialogue then just get the "good job!" and "nice work!" responses.