No problem with those. They aren't any smaller or larger than any others and you aren't above or below a dance floor or open deck. The only ones that differ in size are C1 to C25 and Grade NN on D dec.
We stayed in C9 and C7 and C5 on three cruises that we did on OV1 these are resticted view due to the lifeboats. But have to say there were three os us in there and we didn't find it cramped. So the cabins you have booked are slightly bigger and to be honest if you draw the curtain across the wall you wouldnt know there wasn't a window there. We have done the Greek cruise and found Dubrovnik to be beautiful, you are sailing on the better ship of the OV fleet and I am sure you will have a great time.