Don't think you can rationalize paying credit card APRs with this strategy and end up ahead.You can get significantly and consistently better returns from your investments than you will lose through depreciation.

The problem with general price inflation greater than 10% no rational entity would commit money to loan when economic conditions rendered his transaction a certain loss.  

Chi:Absolutely, if your debt ration supports or can sustain two mortgages then you should be ok.

Helps me a lot to separate and make rational business decisions while not having to be the bad guy all the time.

@Dave ChimobiYou are using a 20% expense ration before P and I and that doesn't strike me as nearly enough to reflect what your experience will be over holding a property long term.

If the closing occurs before the tax bill comes out, pro ration is based on the prior years taxes which may be less then the amount due when the bill comes out. 

Treating it as a business expense sure will help me to rationalize it since I seem to have gotten  into the happen of looking at the ROI of everything I spend on, and dismissing just about anything that doesn't have a financial return.

That's where the majority of REI are looking, finding, getting into bidding wars, and ultimately bidding against themselves...then rationalizing that they got a great deal...somewhere down the road, based on events they have no control over. 

4 - If your plan is to live in the house before you turn it into a rental, buy the house based on the numbers that will make the rental work...without any rationalizations of what might happen in the future that will fix any reason that house won't work as a rental. 

This falls under the category of "sometimes the best deals you make, are the ones you don't".You're getting lost in the percentages...which are leading you to rationalize that this might somehow be a good deal.