The existing mortgage will probably save me over $30k in comparison with my new terms factoring in the remaining maturity with the existing financing and the rate I would pay with a similar maturity.3.

The important comparison to make is what you would earn with the after-tax money from the sale. 

You might not get exactly all you need, but you get a lot of data as a starting point or another comparison set.

Very often high vacancy is a sign of poor management not necessarily a problem the new owner will have.My appraisals generally show a rent comparison.

Try to get comparison for both products. 

The interest paid over time will pale in comparison to your wealth growth with leverage there.

As the owner of 87.5% of the units in that building, you should have a big say in how things are run in that building.Without knowing my numbers, my intuition is that it would probably make sense to acquire the last unit if posisble.However to know for sure, I would  run a comparison analysis between keeping the units separately or pricing the building as a one multifamily.I would use the statements from the HOA to know precisely what my expenses would be.

And when you are ready to outsource your mailings, the only way you'll be able to make an honest apples-to-apples comparison is to know what your actual costs are to fold, stuff, label, stamp and mail each piece.Because I bet you're "paying" way more than you realize to do it yourself.For example, I've used Click2Mail's email-to-mail service to mail 8.5x11 letters in a 6x9 envelope with first-class postage, one at a time, for 84 cents each.

I have some insight from a local property manager on what their complex is short on and I have comp sheets of all the major players for comparison but is there a better way to hone in the mix?

Whether it's done this tax year or in future tax years, doesn't matter to me.I remember years ago Money Magazine would do a yearly tax preparer comparison.