But to the north, west and south, there has (almost) always been a stock of housing that was more affordable than in Boston.But then all of that housing stock kept rising in price, and earning power didn't keep up. 

The prospects for appreciation are limited (probably below the inflation rate), your tenant pool sucks to manage from out of state, your risk is high because you don't know what the heck you're doing - none of us did on the first go; that's not personal - and your flippant verbiage is treating this more like trading stocks than buying property. 

@Wesley BryantHistorical figures showed real estate and the markets are very similar for returnsIf you are more active as an investor then their is opportunity for higher returns just as if you wanted to be more active in the market.The reason why it might be worth one or the other is diversification and investing in non correlating assets.I invest in real estate because (I think) I know what I am doing - and for stocks that is not my specialty.

Maybe local investors as well who want real estate safety vs stock market or commodity risk.   

I'm getting over a 9% return on my stocks and index funds.

There are many great neighborhoods that offer a consistent predictable ROI.

What is your favorite metric (CoC, IRR, ROI, etc.) you are using when comparing your real estate investments to the stock market (or other more passive investment vehicles)?

You cannot predict the future.

If national investment credit tenant even if sales not disclosed in lease often in their corporate website stock disclosures you can find data average store sales overall and then sometimes per store.If no credit you need sales disclosures as tenant strength is weaker. 

Why do you want to pull the money from stocks?