You should have stated MTM for Securities only, this leaves futures at a 60/40 split for you. Don't elect MTM on futures unless you think you will never trade futures again profitably.
greencompany.com have a remarkable and very useful tax education center. I do recall them having a number of articles that address your question specifically. There are also quite a number of posts on similar topics here at ET., some answered by a greencompany.com rep, which is how I found out about their site. Do a search here for "taxes" and it'll put you in the right forum. amg
May 21, 2003 Chicago traders win tax victory By Paul Merrion WASHINGTON â The Senate killed a proposed tax increase for futures and options traders after a furious round of lobbying from Chicago exchanges over the last few days. The original provision had been slipped into the Senate's tax-cut bill without debate last Thursday as a last-minute offset to keep the total revenue decrease to $350 billion. No similar provision was in the tax-cut bill passed earlier by the House. complete article at ChicagoBusiness.com Sometimes the big boyz (with a mob of little people behind them) score a win. Good work on the email campaign!
Some more information as to what took place as of Tuesday evening is in this article: http://www.hedgeworld.com/news/read_news.cgi?section=legl&story=legl1819.html