It's probably not a big deal if you're chilling (mowing the lawn on the foil, throwing some lofty jumps on TT, etc), but when you're pushing the boundaries of whatever sport you're switching too, I think there's something to be said for the muscle memory that has to be retrained when switching styles and sizes of kites. That's just my 2 cents, and maybe I'm just slow, but I prefer feeling confident in how my kite is going to react before I'm 20ft in the air and I need get back down... gently lol
When the winds a bit light for a 12m NV, I'll still grab the 14m apollo, but its always an adjustment for the first 10min on the water or so. After that its a blast and I enjoy my hang glider that floats me back down to earth