as far as what you guys are talking about, its very easy to assemble a "ghetto" version very quickly. take the smaller led's and slide them right on to the battery, once you have made a little star just rap it in tape, and use clear tape to put it on the bottom of the disc.
as for diminished flight characteristics, puting anything on the disc is going to change it, just like hitting trees would. The completed caps are not very heavy at all, and so long as you keep the internals balanced and put it as close to center of the bottom of the disc as you can it doesnt seem to affect it too badly. maybe a little less glide where there is less room for an air pocket underneath, and a tad more overstable. I guess it depends on how seriously your taking these night games. I personally only plan to carry two discs, a putter and a mid. discs that I can throw straight. even if the added weight were significant, heavier just has more accuracy right? sounds good to me.
I soddered 2 of them to the sides of a 2032 battery and then taped the thing to the top of a disc.
Im sure can explain the physics behind it but my guess is that this would change the flight characteristics more than a 5-10 gram bottle cap on the bottom of the disc.