Ok, I have a spokeshave and it sucks for removing belly material. I use a nice draw knife. You have much more control. In fact, the draw knife just gets used to get down to my ring I want on the "back", and belly only get hits with a ferriers rasp at first for floor tillering, then scraped with a scraper. I use a bandsaw to get the bow down to rough dimensions.

If your trying to get the belly down to rough dimensions with a spokeshave, I would go with a straight one. Especially if your making a flat belly design.