My suggestion is to use the auto-sort feature in each slot/page of the armory bag.
I wanted the gear sorted a certain way for a long, long time. Spent great amounts of time rearranging. When I finally gave the auto-sort feature a chance, I found that I could, at the very least, predict where a certain piece of gear would be. The auto-sort feature sorts by: Low-level > High level > Class as far as I can tell. Over time, the gear still gets switched out-of-order, so my habit now is to right-click as I open the page
Although it's not exactly how I would want it, the feature has none-the-less saved me a ton of time since i started using it.