If my memory is correct, green tritium's brightness last longer than yellow, amber, red etc. so I would opt for a green front and the yellow rear.
For those who have experience with True Dot sights, which color combination is best?
I have several Glocks with the green/green combo, and currently own one with green front/orange rear dots. I'm not sure if that is the same as the green/amber combo you listed, or an older combo that is no longer available.
Green/green works fine; I have never had any problems with it. I have one Glock with green front and orange rear, and had another Glock set up the same way for a while before selling it (for reasons unrelated to the sights). Both green/orange sight combos also worked fine, and there is NO chance of mistaking the front for one of the rear dots if you were to get the sights laterally mis-aligned during a draw/presentation; so if that is a concern for you, mixed colors might be the way to go. I've never experienced that problem, even during high speed drills in dim light or near-total-darkness, so I tend to look at mixed-color night sights more as a marketing-driven option than a real must-have. Personally, I put the first mixed-color set I bought on a ported Glock, because I wanted a way to I.D. that one as different from the others, even in the dark. The sights worked just fine in that capacity, as well as being just as useful for dim-light shooting.
I have also heard the lifespan concern that VAMarine talked about (above), and it is something users need to keep in mind. If you want bright, eye-catching dots, you'll end up replacing orange (amber?) more often, perhaps every 5-7 years vs. 8-10 years for the green.
My biggest concern with mixed-color illuminated sights is I want the front sight to be the brightest and most noticeable; I want my attention drawn to the front sight. With the green front and orange rear, the rear is muted/dimmer, so the front sight stands out quite well. I have never used or even seen the yellow dot version in the dark, so I don't know how bright it is compared to the green. If it is dimmer than the green front, it may work as well or better than the orange/amber by my standards; if it is brighter than the green front, then I won't choose/use it.
Hope this has been helpful.
Thank you very much!