Sorry for not mentioning, I made a few other posts today. I'm in Romania, my trip will be in the Aegean, Cyclades. The temperature is supposed to be quite high (close to 100F at shore), so a rigid vest will be unpleasant for the kid. I don't want to make any compromise on safety either.
Lalizas (Welcome to LALIZAS S.A., Immersion suit manufacturer
) have mentioned inflatable are possible for kids above 20kg in weight. Considering it's a Greek company, I suppose standards are different but still, this should be EU compliant.
Cormeum, aren't the inflatables supposed to self-inflate at water contact? I realize you can't rely solely on these, but then the parent should be near.
I will take a look at the Mustangs, but am really concerned about the discomfort in such heat. If you visited Greece you know what I'm talking about.