I have tritium front sights on a couple of my ARs and AK's. I also have/had rear sights that are lit on my AK's, and my experience with them kept me from buying the rears for the AR's.
With the sights I have for my AK's (Meprolights), the dots on both front and rear are the same size. This causes the dots on the rear sight to appear larger, blur, and be out of focus. You dont get a crisp, clear pistol type sight picture with them. If the rear sights vials were smaller, like the vials on a set I have on my one shotgun, then I think the results would be much better.
With the AK's front sight being forward and being a problem, I cant imagine having the dots right up close to my eye, like the AR's do.
When I replaced the rear sight on my one AK with its original rear sight, I found that I could readily use the front sight when the rifle was shouldered properly. This works even better with the AR's, as the rear sight is at your eye, and there are less alignment issues. Its more muscle memory than anything else, and if you dont get the alignment right, you usually dont see the front dot.
I would suggest you just by the front sight and see how it works for you. At least its the cheaper option initially, and if you feel you might want the rear, you can add it later.