There is a paper out there where they compared different products using a porcine model and I think, combat gauze came out on top. This was 2-3 years ago. As an EMT I was trained on Quickclot, and it didn't go over real welll in EMS..We anticipated more usage being a rural, volunteer agency (not enough people, long transport times, higher percentage of non automobile traumatic injury (ie chain saws, woodworking saws, ag machinery)) In reality the stuff was overused and caused a lot of problems. Our On Line Medical Director requested that we make it a schedule B intervention (in otherward you need the MD's permission to use). This was more or less putting us on notice to be very restrictive in it's use. In actuality if you need it, you don't have time to ask. Meanwhile, every day we find tourniquets are a better tool then we thought. Soon after that, they moved to QC sponges (still optional, but you couldn't use a hemostatic agent not on the list.) I think we are still underwhelmed on it's usefullness, but the ER docs are no longer worried about us using it. Combat gauze isn;t on the official list (or the last time I saw it it wasn't), but that's not an issue for most rural EMTs.
So my take is, except for care under fire, the stuff is mostly useful for non extremity injuries where direct pressure requires a responder, and tourniquets won't work.