If you're 210 lbs, I would say for your bodyweight the B4 or B5 would probably serve better, but you never mentioned what windspeeds you'd go out it.
We train on the B2s and noticed that unless there's high winds, they tend to fold a lot. But, when there's good wind, they steer too fast.
B3 is a better choice for training, in my opinion. And someone as large as you will need a good kite to snowboard. I am 190 and use a 6.3m as my smallest kite. (but I'm a bit more experienced). The 6.3 is a Peter Lynn ARC that I use on land (its a foil, too).
The B5 will give roughly the same pull as this kite, but you weigh more than I. The B3 would be too small, unless its 25-30 kts.