Just stumbled upon this thread again. I did it this year.
To answer your questions, I thought the routes were fantastic, and pretty difficult. The organisation was very good, I thought. There was extreme rain the day before we arrived and the organisers were scrambling, dealing with washed away trails etc. They managed to re-route and get GPX files out to everyone every evening. The first day felt a bit chaotic with an extra few hundred doing the French Marathon Champs also but considering all that they did a great job. The race mechanics were great too.
I found the descents challenging but doable. I had no experience with alpine switchbacks and I don’t love exposure. The rain made some trails trickier for sure.
The total amount of climbing and technical trails meant average speeds were pretty low so factor that into training. I wasn’t thrilled with my performance, maybe back to back days and altitude hit me harder than I anticipated.
I’d recommend it. Any questions just ask.