So i Just need to update my "issue" with Bistro 17mm DD/FET driver from MtnE.
the issue was me!
So after making my post here i reached out to Richard (Glad this post exists bc i probably never would've bothered reaching out to Him), and i told him what was happening and my overall experience with having other drivers from him be totally fine.
He responded promptly and briefly and suggested i probably had a short somewhere, because it sounded like my driver was being bypassed considering the behavior it was exhibiting.
Well i took the C8 apart yesterday and reinstalled the driver and checked the tail switch and resoldered the mcpcb with the solder joints much lower and compact, and now the light works PERFECTLY! And what a great driver it is! Running an SFT40 on DD FET with a 10amp panasonic GA 18650, this thing shreds! And i REALLY enjoy Bistro for a thrower - great thermal calibration, selection of well spaced modes from 1-8 (I use 4), no moonlight, being able to turn off half press for "backward" cycle, its all just awesome.
So i am glad to say i never had anything wrong with my driver. What the problem was is that when soldering the board into a C8 (I was using a Convoy board and centering ring which i use all the time, btw), you have VERY LITTLE clearance from the edge of the reflector to two solder pad leads. Mine had to of been touching there, because when i reinstalled everything i tested the light without the reflector and i was getting all of the modes, but when i installed the reflector and bezel the light would only work on 100% output. So, it was shorting out on the reflector.
Anyway, i have had to deal with those tight quarters of reflector/ leads / centering ring before, but usually when im custom installing something, not using the same manufacturers parts for every piece of the build! I feel like that is more on Convoy for leaving such little room to make things fit. But, maybe i just need to sharpen my soldering skills a bit ;)
all is good now though, it was my soldering that made me think i had a bad driver. and i didnt feel right Not coming back here and addressing my previous comment!
-Artie