Space heaters and hot plates are already dangerous enough that allowing double the current seems like a hazard

You'd require half the current for the same wattage at 240v. At most, it's the same 15a max, with double the voltage.

Tbh I think I'd rather achieve the same heat output by running them at 240v using less current instead of 110v and pulling as much current as possible/permitted (15a).

Insulation is cheaper than actual conductors too. Higher voltage and lower current means thinner conductors with more insulation to protect them. You'd also remove complexity and thus cost by only needing one voltage. No need for a split phase supply.

I think 240v would be a better option. 🇨🇦