In reply to shaun walby:
Hi Shaun, what do you mean by 'Original' or 'High Level'?
I've done C > Z a number of times in summer with groups. A couple of times via the Valsorey until I nearly got wiped out going up to the Plateau du Couloir. From then I decided to miss that section out and go straight from Champex to Mauvoisin. That said, any of the wet glacier sections are certainly very dangerous for a solo walker, and get more and more serious as you get nearer Zermatt.
Most days have glacier sections that I would advise against solo:
1 Albert 1er > Cab Trient - lots of crevasses
2 Cab Trient > Chanrion - is OK
3 Chanrion > Vignettes - crevassed section before the Vignettes
4 Vignettes > Bertol - very crevassed up to col de l'Eveque and down as far as col Colon, after OK
5 Bertol > Schönbiel - death on a stick