That implies a couple of things - First that you've got a substantial amount of equity to be used in your next purchases. 

I have recently found a partner within my network who can substantially increase buying power.

If he has some stock in the plan, he can save substantial amount of tax with correct kind of distribution( lump sum distribution) In general, If his family has a business that has expected loss to nol carryover, that would be right time to rollover the IRA as the tax would be minimized or go away.

If you have not kept up on annual rent increases, a substantial increase can scare a good tenant out.  

Time and expense  substantially higher than planned.Plumbing, electrical, bathroom floor replacement, safety code updates, repair/replace rotten wood, etc.  

Houston is hit and miss and while oil prices no longer control that market, they do have some influence, and oil prices aren't helping Houston at the moment.Speaking of pushing rents as far as residents can tolerate--that's a reason why I don't favor California at all. 

They would also have to recapture all depreciation since 2007 which would be substantial as well.At this point they're probably better of selling as an investment property and using a 1031 exchange to move into passive management or better cash flow. 

I can break-even with a 50% cut in gross rents, and am prepared to take a larger hit for 4 or 5 years if we see a sustained and substantial depression. 

I would prefer to stop paying that amount of taxes or lower it substantially .  

And this will influence your market assumptions for future deals.