The Metro is at the heart of the Washington, DC, region's success, and we're in danger of missing out on the opportunity to jump on that train (pun intended). It only makes economic sense, both on a personal and countywide scale, that we say, "Yes, we want Metro."
The benefits to individuals are clear: Money saved by riding Metro rather than paying for automobile fuel and maintenance (easily several hundred dollars per month), an easier and more reliable commute, saved time (households in DC region save the equivalent of $705 million in time savings per year thanks to Metro), and wildly increased property values.
As for Loudoun, Metro is our best bet if we ever want to see any real development come to our county. Since the creation of the Metro, over $200 billion has been added in property values within half a mile of Metro stations, the DC region has been able to mitigate the growth of traffic and avoid an additional $11 billion in road infrastructure spending, and the land value near Metro stations generates nearly $3 billion per year in property tax revenue, ten percent of that being directly attributable to Metro.
Those who complain about the cost of investing in rail seem to forget about the greater costs and fewer benefits of the dead-end solution of building more and more roads. If we want to see more congestion, less revenue, and little development, then by all means let's opt out of Metro. But I would like to see Loudoun leverage our position as a prime part of the DC region (with our very own international airport, don't forget) and choose to develop our county into what it is capable of being.
But to do that, we need to connect ourselves with Washington via a public transit system, i.e. the Metro. It just makes sense.