Sevi and her husband were great - and so was the house and its location! You have everything you need for a great time on Kalymnos!
The only thing to considere for larger groups is that the house is greek style - i.e. thin walls and some beds out in the open/hall (i.e. not separated by a door).
However, since we were all going to bed and getting up around the same time it was not much of a problem.