Well, I honestly dislike 'breed with elemental for 100% chance of DB Exalting!' since presumably, The Realm and Lookshy will do so if that were the case, or there'll be more encouragement to, ah, dally with elemental.
Unless there is horrible, or bad long-term side-effect that's not mentioned, anyway,
Regarding Exigent, I believe it is mentioned somewhere it's main purpose is to fulfill Devil-Tiger role - specifically, having custom Exalted that's unique. More specifically, solving the problem of 'Well, I've written this awesome DT charmset, but I'll need to wait 100+ years if I want to use vanilla setting...'.
Mind you, you can probably persuade your ST to run AU Exalted setting to accommodate your DT as starting character, but speaking as ST, that's frankly too much work. The easiest I can do is your patron Primordial just spawned and decided to Exalt said character, or s/he is part of Yozis. Any other options required rather hefty world-building.
Contrast this with Exigent: There is really no need to rewrite the setting. Simply plop the character, and done!