Should I combine 2 townhouses into 1 duplex? Loan rate vs Deprec.

[Robert Dickens]

I'm buying a duplex in Jacksonville Beach, FL that has been legally separated into two separately titled townhouses, which means I'm currently going through two simultaneous purchases with two separate sellers (ugh).  Each side is $450K.

My plan is to live in one side and rent out the other for a year before moving into a new primary residence and repeating the process.  I can get a 2.75% mortgage rate on the side that's my primary residence and a 3.25% rate on the rental side (a 3% effective rate across both units).  My plan is to combine the two sides under one title as a duplex after purchase and then refinance to the 2.75% primary residence rate on the entire duplex, saving .25% over the long term.

However, I also know that a rental property has certain tax benefits that a primary residence doesn't, like the ability to claim depreciation deductions.  I've never owned a rental property so there are likely many other considerations.

The question is, does it make sense to combine and refinance, or keep them as separate townhouses?

Thanks in advance!