Yeah I bought a Philips LED colour changing spotlight (actually Little Mermaid one, much to the amusement of the Mrs, just cus it was cheap) back in June.
In my time with this it doesn't prevent externally tracked drifting issues; or positional parallax errors (which I think is related to rotational drift). It may help with jitter and I think on Reddit this turned out to be the main claim. And all makes sense when you think about the physics involved.
I tried testing Farpoint on the first challenge level (Descent?) because I could see a reasonable amount of jitter on the gun in that level. I tried green, blue yellow and orange and couldn't definitely say there was any improvement, perhaps orange was the best and was the colour I stuck with.
At least part of my problem was that the jitter of the Aim controller is the combined jitter of the HMD and the Aim controller which together uses two sets of differently coloured tracking lights.
Perhaps the best way to implement is to just concentrate on the HMD, perhaps testing with a Diorama style game to better illustrate jitter?
I really wish Sony would release a tracking utility solely for the purpose of helping to refine the tracking environment. Part of the reason we get bogged down in all this setup and test malarky is because its so difficult to objectively verify if one setup is better than another.
One thing I have definitely established for myself is that if you need to cover a mirror use blackout material, normal fabric is not enough. I had a mirror directly behind me that I would cover up with heavy fabric. Then a few months ago I realised I could reverse the mirror without too much hard work, and the difference in precision is substantial.