I'm glad you suggested Laurent Petitgirard because unfortunately I can't get into the more 'avant-garde' operas as much as I want to, and I do try. It just isn't for me.
I'm quite interested in Laurent Petitgirard as well. While I quite enjoy any number of musical works that fall under the more experimental or avant garde rubric... including some operas, I have long despised the notion that the extremes of artistic experimentation represent the only art of any merit. The term avant garde is surely something of a misnomer as it denotes the body of troops heading in advance of the army as a whole... and yet none of us knows where music (as a whole) is heading.
One more experimental... and yet still exquisitely beautiful opera that I have come across is Pascal Dusapin's
Perelà, Uomo di Fumo:
The entire opera is actually available (right now) on YouTube (although it is just the sound... no video):
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