Are you just trying to play for the EV from the bonus, or are you handicapping? There's not much EV left from simply doing sportsbook bonuses these days. However, if you're closer to a breakeven handicapper, you can do a lot better.
Well, the problem with this is that the rollover is usually enough for the juice to completely cover the bonus. So you need to have some handicapping skill, or look for differences in the line.