Assent has great rates and I work closely with programmers to create trading programs that my trading group uses each day. My group leader answers all questions and addresses all problems promptly.
Cons
Help desk is pretty much worthless as they are at most prop firms. Sometimes I feel like I am doing them a favor by pointing out a problem that affect all of us. The software is a little dated, but that is what I am use to having traded this platform off and on for the last 10 years.