I was given demonstrations of MLX and Tradespeed over webex a while back. Both seemed like good execution softwares. But neither had charts. I recall that Tradespeed charged a per share rate on top of your clearing rate from Merrill, so it can be an expensive piece of software if you trade high volume. MLX was free. I chose Sterling because it had charting and some other little things the others didn't, and it was being used by more people than the other two softwares were.
I second the statement that you should call and ask Merrill. They should give you a demonstration of the other softwares just like they did me.
I second the statement that you should call and ask Merrill. They should give you a demonstration of the other softwares just like they did me.