"A Time of Death" played first in a non-Ripper battle, but it is still kind of agreed to be his theme, if only because of the name. I don't remember "Haste" at all, gotta listen to it again after work. Fighting against Touya in Magical Beat instead of Es kinda serves as evidence to your point, so you convinced me there. I didn't really like the gameplay of Magical Beat, so I didn't play it enough to know.
I totally don't share your opinion there, we've seen a great variety of songs in fighting games, and especially in P4AU we have a lot of songs mixed together from different directions, that are hard to imagine in a fighting game but end up working perfectly well. ("Reach out to the truth", "P3 FES", ...)
Whether the same would apply to BlazBlue, I don't know, but we already have some OST in the game that is 'different' and doesn't seem to fit the fights too well. ("Catus Carnival", "Active Angel", ...)
Edit: Not that I mind the idea of Es' theme being something completely different from the XBlaze OST. (The whole OST would fit in UNIB pretty well (not that it matters, I just realized that))