Sidesaddle. I have heard that the Speedfeed stocks, while a nice idea, don't work all that well in the field. The sidesaddle is a good (and economical, around $20) solution to the problem of convenient carry of ammunition.
Surefire is the way to go with shotgun weapon mounted lights. Recommend getting one with the parallel mounted switch ("F" suffix) for defensive uses. Places to buy include Lagger Pro (http://www.lagger-pro.com), Brightguy (http://www.brightguy.com), Botach Tactical (http://www.botachtactical.com) and Maricopa Tactical (http://www.maricopatactical.com).
HTH,
Justin
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Justin T. Huang, Esq.
late of Kennett Square, Pennsylvania