I keep most of my better/long term wines, and most champagnes which I've heard are more sensitive, in a carefully regulated fridge, in the basement, and the rest are stored in a setup similar to what you described, also in the basement. I've never had a problem with anything that I could really attribute to the storage conditions. The temperature is never far from 55-65 degrees depending on the season and never fluctuates fast enough to do any harm that I can see. Like The Prof said purists may cringe but it works for me.
Other things to consider while you're gone. Is there a possibility of the basement flooding? It might ruin some labels but shouldn't bother the wine. Insurance coverage/rider for the wine in the event of a fire or theft? Any chance of a big storm and a week without power in the winter when the stuff could all freeze or is there a back-up generator? We had that last December here and without the generator a lot of my wine would probably have been lost. Freak stuff I know and if it's all covered then no worries I guess but things like that would make me look twice at off-site storage if I was going to be gone for years.