I make, sell, and use angle peens hammers all the time. The big advantage is their ease of use. With the peen offset at a 45 degree angle, you stand naturally, rather than having to twist yourself into a ball in order to get the job done.
The "Double Drawing" hammer allows you to draw both lengthwise and side to side simply by flipping the hammer over. An added benefit is that you can draw edge bevels without having to back bend a blade.
Here's a link the my
Hammer page