There's certainly other aspects that you need to consider such as pricing, quality of photos & overall listing, is it clean/repairs are done, if there's tenants are they being decent to people during showings, are you requirements reasonable etc... 

Will the Elastomeric look good and hide aesthetic imperfections like rust marks?

Some contractors have insurance, some are 1 man band with no overhead, quality of work factors into cost, level of finishes.We created a calculator for our clients to use here in Chicago, specific to our renovation pricing, but even that is just a guess based on some assumptions.If you can find a quality general contractor, pay them like @Bruce Woodruff mentioned, and it will make your life so much easier...you may eat into some of your profits, but being able to rinse and repeat with someone you trust is priceless!

Managing contractors and verifying quality of work/timelines can kill a deal.

Are their listings detailed with good-quality photos?

I tend to favor buying a few high quality properties in  coastal CA (Bay Area, LA, San Diego) over buying lots of less expensive properties in other states. 

This one is/was a C- or worse at the beginning and now they would be about a B quality buildings in a Cish neighborhood.

This one is/was a C- or worse at the beginning and now they would be about a B quality buildings in a Cish neighborhood.

I definitely recommend that you seek out a Certified Cost Segregation Professional so that you are confident in the quality of the work performed and the deliverables produced.

I agree it is a tough decision, but at the end of the day, this is a business and they should live where they can afford to live, whether that is on your property or elsewhere.That being said, you have every right to improve your property and allow for a better quality of life for someone.