At least seal it with mortar or something on the sides of the house to avoid water intrusion (maybe once a year or so before winter). 

In my area, it is much more difficult to find renters in the winter, so I wouldn't want to expose myself in Nov-Feb by offering a MTM lease.

It had been damaged during some bad winter storms and we were unsure on fixing it or removing it.

I'd rather have the property have gone through a couple of harsh winters!

We maintain the houses/apts and are attentive to issues particularly of a serious nature.The winter before last we had two issues with furnaces not working on a Saturday night, one of which we had a service man there within 1 hour. 

Lots of snow in the winter though :)

In winter?

You'll get insane prices over the winter holidays, but may have a lot of vacancy in the summer.

I understand that the electric heat pumps are not efficient at lower (winter) temperatures, which we have a lot of in Philadelphia winters.Are the newer models as bad as some of what I've read online?

I am in the process of finding and purchasing my first multifamily investment property scheduled for the winter months.