Thanks Mike. For really light winds, I co-own an older Cabrinha 16m ... it starts to work at 8kts, fun at 12-15, and you would not want anything to do with it at 18kts or more. I suspect the BWS 12m might have similar wind range or at least top end. The upper end of feeling safe with my Cab 12m is maybe 24kts -- think the BWS 12m might be 18-20max.
Typical summer winds around here are 15-25, which falls right between kite sizes. You're right, 10m is probably the answer. But I've already blown the budget and won't be buying that any time soon! So for now, I think the plan is to keep my Cab too. So much for my pre-purchase promise "but it's such a good deal honey, I'll sell all my old kites and it will nearly be an even trade".