Good question. In my opinion selling now is the best course of action. The reason is simple: supply and demand. As of today, there are just 19 condos for sale in Somerville and 22 in Cambridge. In 25 years of selling homes in Cambridge and Somerville I have never seen the inventory so low. The demand for housing right now is great and most sellers are getting multiple offers for their property, and I do mean MULTIPLE!
Two years from now I fully expect there to be more sellers putting their homes on the market . I say this because by that time buyers needing to trade up, that purchased at the top of the last market cycle, will have more equity due to the rise in prices happening now. With those new sellers finally entering the market there will be an easing of prices. Prices will still be rising two years from now, but not anywhere near the current pace.
Now here is something else to consider: what will be the condition of your place after being rented for two years? Most tenants are responsible but typically not to the same extent that an owner living in their home would be. You may need to put some money into your loft to get it ready to sell. If the tenants have moved out in two years you will most likely have to paint as well as have the place staged.
Hope this helps!