Our pastor usually sings the entire piece, but he has had numerous health issues this year. He sang the first parts, then read the rest. It was a good idea to not get so winded on this one piece that he couldn't function for the rest of the Vigil. No harm was done by this, and all worked out well.

Bulleted thoughts-
*Due to the singular importance of this one chant as a prism that opens up the new Christian year, its assignment to be properly rendered cannot suffer one dimensional consideration, ie. a pastor/celebrant only, a deacon only, a cantor only, a choir only, etc.
*It ought to be the Missal version if at all possible. Versions chorally arranged like J. Michael Thompson's wonderful homophonic version need to still be rooted in the missal chant. But an unaccompanied (and if possible, unamplified) performance firmly sung, annuciated accurately, unite the elect with the community and the company of angels and saints, lit by Christ our Light through the centrality of the Paschal Candle, blessed and processed.
*Like canting the Passion or other/all lessons, I personally don't think that either an operatic modality (and certainly not bel canto) or a precious, too soft and lyrical/quasi sotto voce rendition serves the intent of the proclamation. But one doesn't want to advocate a masculinity as sometimes intimated by C.Bartolucci that to me, suggests a brutish approach.
That's my take.

I remember a fairly well-published priest composer some 25 years ago who sang the Exsultet; he was a fine pianist and a light tenor, but he was so eager to avoid going flat that he ended up modulting up at least a major third over the course of the chant, putting him noticeably into not-so-great falsetto land. If he had presence of mind at the time, he could have paused and asked for the incipit to be re-set, as it were.

The way you deal with things like this is . . . musicianship. (Then again, I was trained as a horn player. You *will* fail with the horn; it's built into the beast. My favorite story of this type regards a concert in the 1970s by Barry Tuckwell that my horn teacher shared with me: Tuckwell flubbed a very exposed high note - he paused, pointed his finger up into the air - and the four horns of the orchestra hit it for him. *That's* musicianship. It was contrasted by the behavior at different concert of a Continental horn player who flubbed a high note and, after the concert, hurled his Alexander down the stairs to the sub-stage area). Elemental musicianship can be seeded into non-professionals by illustration and permission ("if you feel you're losing the pitch, just nod for an incipit. It's perfectly fine.")

Booing and/or whistling are not an option, so unless one is in a position to hire/fire the answer is clearly nothing. There is a lot to be said for muddling through, especially if one is not encumbered with an accompanist. Piatagorsky writes of a memory lapse at his Vienna debut where he improvised an entire prelude for a Bach suite. A long line of excited cellists at the reception were eager to learn what edition he used!

I personally don't think that either an operatic modality (and certainly not bel canto) or a precious, too soft and lyrical/quasi sotto voce rendition serves the intent of the proclamation.

The Goldilocks approach sounds so reasonable that I feel like a Devil's advocate to take issue, but why exactly wouldn't one adopt bel canto in a church about the size of an opera house, or resort to crooning if the microphone had no off switch?

The Exultet was the first chant I ever taught myself. Rehearsed probably LITERALLY 100 times. Nailed it, learned from it, and though I'd love to do it again, I ferl it's better that I never ever do it again.

My Wagnerian experience stood me in very good stead indeed when the lector started rummaging about my feet for something or other with an open candle flame.

I don't want to know.
No, wait, i mean I REALLY want to know.

(Save the Liturgy, Save the World)

...the task assigned to me without affectation.

or dilettantism, I would presume. I know you at least wouldn't argue church music deserves less care than the theatre, though that seems to be the general rule. I do have a beef with treating bel canto as a dirty word.

G, nothing as picaresque as you seem to be assuming ;-P, nor did anyone at church die by a spear thrust. The wildly leaping shadows though were as distracting as any smoke machine at the end of Walküre. I never found out what was being sought; probably they were afraid something was unplugged.

I don't really like bel canto singing when I'm at an opera...