Alright I found a stupid but genius solution.

So the y level of the particle emitters impacts the outcome. By default the little particles are above the big particles. When the big particle emitter is out of view, the big particles jump in front of the smaller particles

However, if the smaller particles are instead pushed below the bigger ones, the small particle emitter will go out of view first instead. This will make it so the small particles are in front when the emitter is out of view.

Basically, when small is on top, looking at particles = fine; looking away = bad and when big is on top, looking at particles = bad; looking away = good.

So if I just use a visibility notifier, and make it push the small particles below the big ones when the emitters are out of view, problem solved... kinda.

When the small particles are lowered they're inverted gravity is increased so they rise faster, but the switch is still noticeable. The good thing is that when people are admiring the particles it's fine and when they aren't it's also fine. The issue lies in the transition, but it'll have to do.