Sure, you'll get the occasional person that has a problem with it but honestly, do you want to work with anyone like that anyway? 

That is a dam tough job.We occasionally still have arguments about real estate, but not very often, despite buying for 25 years. 

I do occasionally borrow against my 401k for real estate, but again, it was a standard employer plan (back when I had an employer). 

Another concern is that the occasional flip will be fully tax sheltered, but a repeated and focused use of this strategy will create significant tax liability even inside of an IRA or 401(k) plan. 

If you'd rather have a bit of a buffer for uncertain times, stay the course or make the occasional extra payment.

Repairs, CAPEX, vacancy, the occasional crazy tenant who steals your AC when he moves out. 

What's NY and Philly got that Pittsburgh (occasionally known as "the Paris of Appalachia") doesn't have?

Yes, we check email and make the occasional phone call while on vacation.  

You will obviously repair things that are non-functional (bad outlet, stove burner is out, or other things missed during your inspections) but any requests for improvements should be denied.Yes, I will occasionally make an upgrade for a tenant but ONLY after they've lived in the home for a year and proven themselves.

(occasionally it works out for both evenly).