I see what you mean. The only difference I could see was that the stalls could sink rapidly (at least relative to the size of the kite). Is it possible to hold a stall with this?
I must confess that a small bit of me buys full size kites out of the feeling that I get "more" but that does not always correspond to how much fun I have with a certain kite. On the other hand full size is full size... I don't know. Fun to see this little kite (Eolo sport 37?) in action (and that it was not a Micron or 4D that was small for a change).
Thunder and lightning are nothing to play with - best to call it a day if that is in the sky!
Weight when wet? Really depends on winds more than anything. If you were struggling to fly before the rain, then certainly a heavier sail will be really hard to fly. May have to use a different sail (going from vented to standard).
Just be aware of this though - a wet sail may stretch more than a dry sail. Will it return to original shape? - depends on the fabric used. Sprinkles usually aren't too difficult, it's the full on rain that gets tiring. YMMV