It is much more important to know why the score is low and what the prospect is planning than the score itself.

Low refi appraisals are real right now and the easiest fix is to underwrite the refi like you are going to get a conservative as is value plus maybe half the improvements, then treat any upside as a bonus.

My principal and interest payments are about $2,400/month combined, which is low compared to buying my home again today.

Absolutely not.

Quote from @Myrna Gourgy: Absolutely.

I am a big proponent of paying cash for low value properties.. generally speaking rents are lower and there is not enough gross rent to cover cap ex over time when U put max debt on them..

All I can say is you absolutely can cash flow in todays market even with low money down loans.  

When you see an appraisal come in this far off from both market reality and recent like‑kind properties you already own, it’s absolutely reasonable to challenge it.

That amount is not low and I don't think is so low that you take a big hit on rates.

Alternatively, if you find the right deal absolutely partner with someone.