Refi Owner-Occupied as Primary or Investment Mortgage?

[Jason Slater]

Hi all, I could use some help understanding the options and implications for my conventional refinance choices.

For the last six years I have owned and occupied a two unit house in Massachusetts and rent out the other unit to cover a big chunk of the mortgage. I purchased at 10% down with an FHA loan w/PMI but now surpass the 78% LTV to refinance as a conventional loan. It is definitely in my interest to do so as I will drop PMI and about 0.75% off my rate. I have saved the 20% down payment for my own SFH and plan to buy & move sometime in 2016 then rent both my current units (they will cash flow, better than $100/door). I will probably continue to occupy the two-unit for another six months this year before finding a new house and moving out.

If I refinance the two-unit mortgage in the next month or so should I just go straight to an investment property loan or should I keep it as a primary residence loan? 

Obviously there are a number of factors, such as being able to deduct mortgage interest on my primary residence which I assume I can't do if the loan is for an investment property, regardless of if I live there. I have also found through reading on BP that if I get a primary residence mortgage on it then I probably won't be able to get a new one for my next personal home within 6 or 12 months. I'd like to avoid having to refinance (fees!) the investment property again when I buy my SFH residence.

I'm looking for any advice the BP crowd may have on the best choices in this situation. I also know enough to realize I probably am missing some important consideration(s) so please let me know if that is the case. Or if I'm making a bad assumption then I'm happy to be corrected.

Thanks for your time everyone,

J in MA