I don't think you'd feel any difference. People tend to think a 49 rides very differently from a 47. I went from a 55 to a 59 and to be honest the differences are so marginal that you wouldn't really feel them if you didn't know you're on a different size.
Of course, a 49 should give you more stability going fast but it won't change the feel of the board in a dramatic way. Go with the 49. It's not at all out of your weight range.