Hmm. You're probably right. I've experimented with different tunings but I didn't play anything purely melodic. The effect is probably a lot more apparent when you're dealing with intervals rather than just pitches.

That said, changing the central pitch that the temperament is based around makes the differences bigger again; but that's not too useful as a tool for actually creating this melody. I think it'd be noticeable for the arabic tuning system too; that's extremely different to Western temperaments.