In testing the bags they were used daily for two weeks to carry a full assortment of instruments to school each day by an elementary school band director. The bags used were the flagship F1 model, and all combinations of use of the Fuze-On accessory and laptop bags were included in the test.
Overall the bags did very well in terms of protecting the instruments and comfort of carry, especially when used in backpack mode. The shoulder straps are some of the most comfortable shoulder straps I have ever used. The pockets are big and roomy, and in the F1 line additional zippered pocket inserts allow for even better organization and storage of instrument accessories.
For larger accessories such as mutes, laptop computers, instrument stands, and other items the add-on accessory bags are quite roomy. The laptop bag itself is incredibly comfortable to wear and provides excellent protection from normal bumps and scuffs. The only significant issue I noticed while using the accessory and laptop bags is that they tend to make the wearer feel out of balance when attached to an instrument bag piggyback style. In other words (especially when carrying a heavy laptop) the extra bag shifts the user's center of gravity enough that carrying both in this configuration for any distance becomes uncomfortable. However, it should be noted that the bags were filled with all the normal teacher materials, notebooks, and other items as well, making them heavier than most single instrument users would require.
Another drawback for US consumers at this point is that the Fusion brand has yet to be offered by any major US retailers. Several distributors are in talks with the company however, and when the bags become readily available they will certainly make excellent replacement instrument cases for both beginning musicians and professionals alike.