Yes, I had the full Annihilator set, but only used the bracers. At level 16 I equipped the full Mining Guild set, and the bracers were the only piece of equipment I could use from the Annihilator set that was an upgrade and which would not break up the Mining Guild set (which was better suited to my character).
I didn't start out determined to use the complete set, but comparing various combinations of random equipment and set pieces, any equipment pieces that may have been slightly better in some respects to the Mining Guild set were not good enough to justify a drop in the set bonuses (especially wrt bow damage). Each time I equipped another Mining Guild piece, it made the other pieces a little more desirable (ie when I first looked at the Mining Guild earrings, for example, they were not quite as good as the set I had equipped; after equipping another couple set pieces, the extra bonus did make them slightly better), and eventually I equipped all the pieces. Conversely, once I had one piece of equipment worth breaking up the set for (the Bow of Orobas), then all the random stuff I had been collecting became slightly better in comparison each time something in the set was replaced, leading to everything in the set getting upgraded at once.
