Hello @William George, Both neighborhoods you have mentioned have always been working glass stable neighborhoods. With that said there are a few blocks in each of these areas that were a little rough.
With respect to Mt. Airy there is an East and a West. The two are not only separated by a street boundary but by income level. I won't go into a lot of detail here but there are some statistics about this are (population, voting participation, income levels, and homeownership, travel time to Center City, and employment opportunities in the surrounding suburbs) you should consider.
Tacony is an historic neighborhood 8 miles outside of Center City with the Delaware River as one of it's boarders. I don't know if New Yorkers are buying in but there are two things I know for sure. New Yorkers are coming in on buses, previewing Philadelphia real estate, so what this person told you may be true. Secondly, a significant number of Russians are buying and moving into this area. The Northeast historically has a large population of immigrants. It is one of the most diverse areas in this City.
From your post, I assume (and forgive me if I am incorrect) that you may be new to the City. I would be happy to share as much as I know about the neighborhoods you are researching. Also, I have previously posted a lot of information about Philadelphia and its neighborhoods. I am sure a quick search of my name will bring them up.
If you decide to pass on one or both of these deals I would appreciate it if you would consider passing one or both on to me.
@David Weintraub, Philadelphia is having a serious problem with school performance throughout the City. I think we can point out a "bad school" in any given neighborhood based on our perceptions. Where you preferring to a particular school in Mt. Airy and why do you consider it or them bad?