Thanks for your contributions / questions...

The house in question is a two family RENTAL house, with one apartment
downstairs, and one apartment upstairs. Two zones are downstairs, and
two zones are upstairs. My intention was to remove the two upstairs
zones. And have electric baseboard heat installed.

Here is my rationale:

A) I like to have tenants pay for their own heat for two reason: #1
it makes the rent look lower and is therefore easier to get tenants,
and #2 Tenants will naturally be more careful with the heat if they are
paying for it, therefore it is less wasteful. (I tried setting the
thermostats to 70 degrees, then using a cover so the tenants could not
adjust the heat. For some reason this made the heat not work
correctly. I removed the covers, now the heat works fine. (I had an
HVAC Professional come in to confirm there was no other problem. He
recommended removing the thermostat covers, so I did.))

B) Last winter, only the downstairs was heated, yet the upstairs
remained around 60 degrees all winter. Therefore I suspect that the
new electric baseboard heat will not have to work very hard to maintain
70 degrees.

Those are my thoughts... I welcome any comments, thoughts, experiences
etc. that you wish to contribute... Thanks...