Wow. That was fast. I wasn't going to keep this post and whamo! Here it is in a quote. That's okay. I should of kept the original post.
Not with IB.....I currently trade 8 markets with Open E-cry. All the DOM Waterfall/Ladder type of platforms opened up....and ticking away....all for me to monitor and/or trade with one-click execution. These are free of charge and written in C++ with no secondary connection. Michael B.
Better than most if not all of other IB API's as far as trading multiple markets is concerned. Still in the development, but getting more and more mature. You need only one platform open and can trade all the markets you wish for only several bucks a month. Do some search on this board for the Zeroline Trader review.