I am working on a homemade using a pair of XPG r5s, trying to get the all up weight down to under 100g with a 14500 cell but it will be close. Hopefully finished in a day or two...
The xpg's should make quite a big differance for the typical plastic case manufacturers. A lot more lumens for the given curent and also they should be able to up the curent a bit over older designes because there is slightly less heat being produced with the improved efficentcy. An old design producing 100 lumen should be tweakable to 150 without much work.
Having said that I don't think we will see any mainstream for a good 6-9 months.... only the specialists I expect Zebralight to be along befor 6 months.