The wind range is slightly lower, but you are not going to fly a stack indoors (except for a stack of indoor revs).
Thanks, Kent -- that answers a question that's been rolling around in my mind. I've got a B1.5 full sail and a B1.5 mid-vent, and I was wondering when I could fly them as a stack. Sounds like I should fly them at wind speeds that would be OK for either kite flying on its own, and they might go a little lower. I guess the stack is a bit more efficient because you've got more sail area sharing a single set of lines, but then there's the weight of the train lines to consider. I understand that in that case the kite with the most venting goes in front and the kite with the most sail goes in back.
Now I just have to wait for the bridle line and sleeving that I ordered to make the stack lines and heavyweight fly lines... five weeks ago. The first order got lost in the mail, and the post office says that the replacement was delivered on thursday... but I haven't gotten it. That's three packages of kite stuff that have gotten lost in the mail for me so far this year. Just my luck! How does that still happen in the days of GPS, tracking numbers, and text messages on delivery?