I think the one month rent plus payment until the unit is rented is fair.

Its CMA system is fairly accurate, but the free lead lists and the easy use of marketing and sending letters and postcards is also nice.

I had read 50% is a fair number to use for calculations which would raise the NOI by, drumroll...15%, but this is purely speculative) and perhaps the funds or energy to go through an upgrade if they're looking to get out of it anyway.

Not many accounting and PM software do this but any accountant who understands PM and CAM will know what to do.I've done my fair share of CAM recs. 

Allentown, Bethlehem have been sluggish in price terms (6% and 2% respectively above their 2009 'fair value' levels).

That's a fair question, so I went back and checked.

So I have gained so much from just participating at a fairly low level for a few years, but the people I've met and things I've learned have proved invaluable. 

Can communications via email (ex: deposit return letter, or sending invoices) be considered formal and written communication? 

One can calculate the expected roi based upon cash flows and appreciation and that is fairly easy to calculate.

These guys can be larger and clunky when it comes to appraisal turn times as well as overall communication.