Just to repeat some of the most important points:
In regard to taking weight off your shoulders, the stiffness provided by stays or a framesheet is only important as a means of transference of pack weight to a hip belt. If there is no hip belt, there is no benefit to your shoulders. If the pack has no stays or framesheet to stiffen it, there is little or no no benefit from a hip belt. The stays and the belt must work together.
If the hip belt is misplaced around you waist (too high), then the transference is partial and inefficient. If the torso length of your pack is too small, it will not allow the shoulder straps to 'float' above your shoulders, even when the hip belt is properly placed to rest upon your pelvic girdle, making the transference partial and inefficient. The transference is also impaired if you hunch forward too much. You should be upright and the hip belt pulled snug.
When everything fits and is working properly, the shoulder straps should press against the front of your torso, as the pack is being prevented from falling backwards, away from your back. The point where the shoulders straps attach to your pack should sit higher than the top of you shoulders, and the shoulder straps should not actually make contact with the tops of your shoulders at all. All the downward weight of the pack should be supported by your hip belt resting upon your pelvic girdle.