Ah, Finland iss pretty bleak for headphones shopping, unless you like slightly over priced Sennhesiers ;D I've purchased all my headphones from abroad, usually on trips to other countries or then just via webshops.
As for A700 to A900 comparison, I havn't ever properly tested them, but they are the same size. Huge.
If your at all looking for a slightly more portable setup I would go with the m50's. The sound signature is better suited for louder environments aswell. A900's do easily get drowned out by any sort of mechanical noise or rumbling like in a plane or on a bus.