Mini Splits vs sperating Ducting

[Timmery Bors-Koefoed]

So, we recently purchased our first home in Rochester, NY. 

  We plan to rent out the upstairs, a 1 bedroom apt, but currently it has 1 hvac system. There are 2 gas meters and 1 electric meter. The furnace and ac need to be replaced, and we are debating how to seperate the zones for upstairs and downstairs so we can rent the upstairs, we live downstairs currently, but will eventually rent both unit.

We are looking at 2 options for this, but also open to other suggestions. I'm still in the beginning stages and haven't gotten exact quotes yet, but have a ballpark idea of what we're looking at.

Option 1:

Separating the existing ductwork to 2 zones, and adding a second furnace... Tenants pay gas bill. We still cover electric in rent.

Option 1:

Adding mini splits upstairs and including electric in rent for both tenants. Gas would still be seperate. So downstairs tenant would have a furnace, but we would have to increase the rent upstairs to cover additional electricity for the heating and cooling of the minisplits.

Option 2: using existing ducting, we have been told will cost close to 10K more than mini splits. 

Is it worth spending that much, just to not pay 1 tenants heat, we would still pay electric.... I know when people aren't paying they use more. But, I feel like 10K on a 1 bedroom apartment is a lot. We do have very long, very cold winters. I just see it taking a very long time to recoup costs. Also, are there any other factors to consider? We are totally new to this and appreciate any advice. Thank you!