Ok... this is ALL going to be my opinion only... based on limited experience with dyneema in other areas of endeavor and polyester (Dacron) specifically for bowstrings as well as other things.
Dyneema is micromolecular polypropylene, polypro is the stuff in that really low cost, low quality rope that always frays with lots of sun exposure. Now the micromole form is MUCH stronger that the regular, but still polypro. As many of you know. My biggest issue is with the UV vulnerability. I spend lots of time roving and, in FL, the UV is right up there at flamethrower levels. So I just can't bring myself to trust it so much. Keep in mind, JUST my opinion.
Dacron, polyester, is much more UV resistant. I prefer B-50 for the same colorfastness issues raised previously, and having a LOT of German heritage going, I tend to overbuild my strings. A little longer in the strand lengths, a bit more length to the loop and splice-together areas, etc. The one thing that I do before getting serious about tuning is to twist the string to about where I think it needs to be, and then loop it onto a hook that I've got screwed into a post and then stretch the bejeezus out of it before ever putting it on the bow. The ONLY string I've ever had elongate on me is the one that I recently made for an osage stickbow that pulls 100 @ 27" that I'm almost able to shoot properly.
Sermon ends....... :-)