I did not have a chance to taste the leaves of citrus medica, citron to see whether or not it fit my cookling needs. I would appreciate so much if you can describe the taste of a citron leaf compared to a lemon leaf.
Citron leaves are very lemony - maybe half like fresh-cut lemon and half like lemon disinfectant cleaner - but the fragrance & flavor is more mild, cleaner, and less harsh, than lemon leaves. Citron leaves smell more like something clean that could be used in a perfume, whereas lemon leaves smell a little more in the direction like other citrus leaves (I mean a little harsh, petitgrain-like).
I believe citron leaves would be superior for cooking with than regular lemon leaves, but I could be wrong.
Unfortunately there's no way citron will survive outside where you are, it could even be a tiny bit less hardy than a regular lemon tree. There's always the option of bringing it inside over the Winter (though there's many things you'd have to learn about that).