I think the M109 fails behind the bb shell are on older bikes, I have a 2015 CS frame and have been keeping a very close eye on it after being aware of the past issues but having spoken to Whyte was apparently some changes made in the BB area for 2015.
I have the frame from a CS spec with a custom build and it’s somewhere before 23 and 24lbs including a dropper. It has a bit of XTR, Next cranks and Crossmax SL’s – with a bigger budget you could save a bit more weight, I built it with reliability in mind.
Before I got it I tested an Epic and an Anthem too but went for the Whyte as it was more fun than the Epic, though not as fast and I could get the the size I wanted the Anthem in but on my test loop the Whyte proved a little quicker. The 109 has a bit more of a ‘traily’ feel than the Epic and the frame is a fraction lighter (S-works excluded), the life time support on the bearing is appealing too.