I use the X for all my chins, pulldowns, and seated rows. The construction is great and the weights are balanced. And it makes a huge difference to be weighted down on any movement that wants to drag you up or forward.
I used to start my chins with body weight. Now I have the vest loaded at 50 lbs and that has become my first set.
Little tricky getting it on and off. I use one arm of a dipping bar like a hanger to get it on and off.
One of my back routines requires I wear it for 10 sets of 3 diff exercises. It is surprising how dam heavy that thing gets as you walk around and change plates and pins.