Other than Flame-Vault, Bazaar, and Psychatog, is anything even affected by BTS? A 3/4 for 3 is nothing new in this format...
I see Gifts, Stax, and Storm combo pretty much ignoring your only reason for running this manabase...
I was thinking more along the lines of Fetchlands, Wastelands and welders being widespread activated abilities, the ones you mentioned are just added bonuses.
U/R/G Threshold is probably a deck that can accomplish everything you want to do but better. You might want to try the WEE DRAGONAUTS in there too. Cunning Wish for a Berserk is bringing lethal half way there. Just some random thoughts.
I had no idea URG thresh was even a viable archetype in t1, i knew of it in legacy but i have never even heard of it in t1, can you link to a list from a tournament or something i'm intrigued.
The Dragonauts are interesting, but as with threashold you have to build a deck around them, and they aren't always good in the late game after an attrition war. They don't really do anything by themselves. I think they are a really cool creature and i like that draggronought list but i don't think they belong in here.