The Quantum Leap Brass set does *not* have any loops whatsoever on the discs. These are just sampled sounds. I believe that it is sold only as a set (6 discs for Akai I believe) and covers all of the bases.
Disc 1 - Solo Trumpet
Disc 2 - Section Trumpets plus Piccolo and Flugelhorn
Disc 3 - Trombones
Disc 4 - Saxes (no sections just solo Tenor, Alto, Soprano and Bari)
Disc 5 - Tuba and French Horn
Disc 6 - Sustained Loops from all of the discs
You'll notice that Disc 6 has sustained loops. That's right, the samples are unlooped but are long samples. They take a little bit of work to use but are simply amazing after you've spent the time. Once you set up some patches to work the way you want, you'll have setups that work for you.
Trust me, they are really great. There's straight sounds, swells, falls, shakes, muted horns, etc.
Very much suited to pop styles, rock, hiphop (you'll need to make them a little dirty sounding for this), jazz. Some of the other orchestral sets available are more suited to orchestral type music IMHO (that is, if that is the kind of music you mostly do). If you need to, they will work fine in that kind of arrangement.
Trust me, I was floored when I heard them at a buddy's studio. I resist buying sample CD Roms myself but this one is on my shopping list and I'm saving up for it myself. You should check it out if you have a EastWest dealer near you. Otherwise, you can either listen to the online demos or order a demo CD from them (it's free but only has one demo of the QLB).