watson 138 or 142

I am sorry to start another what board thread, but this one is more specific. I want an 09 (price saving) Watson. I am just not sure what size. I am 5-10, 175 lbs and ride a witness 136. I ride wake to wake mainly and dont take it into the flats (on purpose that is). I want a board that lands soft. Right now I am go wake-to-wake consistently and the only trick (other than grabs) is a toe-side 180. I am hoping to work on a heel-side 360 in the near future. So should I go with the bigger board or stick with the 138??? Thanks for the opinions.