Ashburn is less centrally located than Reston, but the metro will help to equalize this somewhat. There are condos available for this price range in Reston, but they are older than Westmaren (Shadowood, Southgate, Hunters Woods Village, Chestnut Grove, etc). Once the metro is in place, the fact that Westmaren is newer, may bridge the rest of the gap in desirability/prices. I would recommend holding on to the Ashburn property until the metro arrives - currently slated for 2016. Just five years may be cutting yourself short on the potential gains. If you were to buy in Reston, metro is supposed to be complete by 2013.
When looking at the individual units there - be sure to note whether or not they have polybutylene pipes - leaky pipes would not be fun for the landlord or tenant!
As an investor myself - I don't look to the past for future values - instead focus on your cash flow analysis as your primary item and any appreciation is bonus on that.
All the best!
You have hit most of the points already, the Westmaren Condo's are great, and centrally located. This will be a great investment with the Metro and One Loudoun being built. You are correct about the rent, one just rented for $1200, in great shape. If you would like to sit down and go over your options, I will be gald to do so. I have been living in Ashburn for over 13 years, and my office is located right here in Ashburn.
Long & Foster Real Estate