Rob, I'm near Milwaukee but I get CSN Chicago. It is not in HD 24/7, so if you watch Sportsnet Central, or Bears Postgame, they will not be in HD. However, almost all of the games are HD. The only time the Sox (and I assume Cubs) are not in HD is early in the season, when the Hawks or Bulls are in the playoffs, and those games are in HD. If you can live with that for a handful of baseball games in April, (or longer if we're lucky), then I would say Dish is worth it.
I just thought of something else. With Dish, ESPNU is not in HD. Also, every game I've ever watched on BTN has been in HD.