Theoretically speaking.... the notes are all in the same range with the sole difference being the third a half step different.

So it stands to reason that singing in a major vs a minor key would be equally as challenging or conversely, equally as easy. The only difference perceived by the singer would be a psychological one. A given singer might prefer the minor key but that doesn't make it easier or harder to physically sing.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.