For a soft pedal, I would suspect some air in the lines somewhere..... If you haven't done so already, when you replace the calipers, bleed out ALL the old fluid in the system. Drain as much as you can out of the M/C, refill with fresh, and then flush the lines really well. Even if you AREN'T getting any more air out of 'em..... What I like to do is have my 'helper' pump the brakes up, and hold pressure on them, while I crack open the bleeder valves. This process will 'break loose' any air bubbles that get stuck in the system. (works great) Do each wheel three times or so, making sure you get no air, and that should make a difference.

That said..... The pedal in my truck has about an inch or so of travel, and then very nice brakes. (like, stuff you into the steering wheel......) On my Astro van, with hydraboost...... there is zero pedal travel, and INSTANT braking. According to popular theory, the brakes on the truck are adjusted correctly.... so, I suspect the difference is just in the method of assist.