Does the appraisal value really matter though if it generates a ton of income?

I'd just make sure you have a VERY CLEAR SCOPE OF WORK no matter who you work with.If you decide to use someone besides your property manager, you need to have BOOTS ON THE GROUND that can view the property a couple of times a week at least! 

But we soon came to realize that we could re-rent a unit in a matter of days as long as we had proper notice from the tenant.  

The tithe was given on "the increase" not the total, and I think that is a reasonable look at how to determine what to give on....but again it is a matter of the heart, it is not a law to be followed. 

Can anyone share their experience in this matter?

You had a prior post that seemed reasonable.To complicate matters, check your state.

However, your mortgage company can bill you for their attorney's fees to research the matter. 

Any guidance in this matter will be greatly appreciated.Thank you!

The word you're looking for is "fee" if you want to keep the money no matter what. 

The only opinion that matters is the markets opinion :)