I've decided to upgrade most of my appliances and was wondering about which
size microwave to get. Word over at www.choice.com.au is that the
auto-sensing Sharps are pretty impressive and the express defrost really
appeals to a lazy minimalist like myself. The midsize leaves just over an
inch clearance on each side of the cavity it will live in, whereas the large
will squeeze in with only half an inch clearance. I'd rather get the bigger
unit and it would fill the hole better, but the manufacturer recommends at
least 50mm clearance on each side for ventilation. Now I'm no expert on
ventilation and microwaves, but given the sides and top don't actually have
any air vents, exactly how important could this clearance be?

Anyone got an opinion?