Me, too!
I used the weight vest this morning in Mesocycle 2. I did back-to-back STS workouts and my arms and shoulders were too sore to hold such heavy weights for very long.
I did take it off for the deadlifts, as I find it makes me too top-heavy to do them safely.
I also wear it for the intervals in LowMax, to increase the intensity when I'm feeling strong (which is not today)!