Minisplit Heat Pump/AC versus Natural Gas Heat/AC

Are you doing it for environmental or financial reasons?

What's your usage and energy prices? Have you estimated the price difference from usage already? Would you be able to turn off your gas entirely (saving fixed charges) if you get a HP?

Any particular reason for minisplit over ducted? IIRC ducted HP are cheaper if your existing ducting can be used without much modification.

Are you planning to replace your entire existing heating system or are you just looking to add AC in addition to a boiler + radiators system?

If you're replacing your entire heating system, go with gas heat and AC, or, alternatively, a gas furnace and a heat pump. Minisplits are great, but they're not good enough to be your sole source of heat in Ottawa's climate.

If you're adding AC to an existing hydronic heating system, get the minisplits.