RentOrSell in FL, then Buy in DC

In 2010 I bought a property (townhome) in FL (20653), and in 2012 I started renting it. I'm about to move to the Washington DC area (as renter) for work, and coincidentally the tenants have expressed a desire to buy the house. Some of the numbers are:

Original Mortgage = $104K FHA Loan @ 4.25%

Mortgage Balance: $97K

Mortgage payment+PMI+Insurance+Taxes (all 2014 numbers)+HOA=$1010/month

Rent: $1050/month 

Currently town-homes sell for $127K (same # bed/bath)

I have a desire to buy an apartment in DC if it makes financial sense. The dilemma is that I may need the profits from the sale for a down-payment. I'm not quite sure how the trade-off analysis should be done here. The scenarios I've played in my head so far are:

1) Sell FL property in 2015 if 20653's avg. home value is expected to increase more than in DC . Use "profits" towards down payment for DC apt.

2) Keep renting FL property and buy a property in DC. 

How would one go about this analysis?