Never done a bike fit, but when you mention the Guru fit, i wonder. Do they implement the knee over pedal axle, or do they move you more forward to get more power out?
I have tried alot of changes on my bike and frankly, i really can't swear on what's for the better or even the best.
Most annoying is perhaps that i notice my foot, no matter what i do, would hit the front wheel if i steer that much and foot is forward. This while i'm clipped in the pedals.
I have no problem with my back if positioned aggressive, but my neck asks for eyes on top of the head. I have not solved that one yet