Just to throw my .2BTC in here...

At today's difficulty, it would take you around 10-15 days to recoup your initial investment (in $USD).  It'll take you much longer to recoup your BTC investment, but it will probably still be around 6 months to a year.

I'd keep it and mine it if it was me.  But it's not me, it's you.

If you want to sell, you'll make money immediately, but if you keep it it will probably be worth more in BTC over 2-3 years.