Sounds awesome. I like the fact that you've limited the drops to only pieces, randomized the timers, and randomized the stats. IMO, the armor should retain its ability to have superior stats to crafted, but the randomized armor will make it much harder to get a full suit of it. It the chance of gettin that "phat lewt" is really low, you won't see too many people wearing it at events (like it was pre-Aen revamp). It would also keep crafters in business, but would be a motivator for people to come back and try hitting the boss again.
Would this turn to raid events? no, because they spawn randomly first of all, but also its no different from, say, hitting Madakoo and hoping for eyes to drop. Its also something thats needed for people to look forward to after hitting 250. Piecing together one of each of the suits would take a long while and would provide a goal for many players.
Praha, also brought up a good point in that this last Aen version required a full range of skills. The first Aen was very easy and could be killed with as few as two players. The revamped Aen took a full team and DA, OA, Nuke, Heal, and the various auras that many of the branches give (melee protection, magic and range). Retaining this ability would not only make it harder to kill, but would also encourage people to diversify their skills (instead of everyone doing melee, nuke, heal)