Well it was the choice of Roman nobility but it wouldn't be my choice.
For a start, I'm unconvinced that zoplclone is a powerful enough sleep agent for what would be a fairly lengthy death. It works well in sending you to sleep but it's less effective in keeping you asleep.
Secondly, I wouldn't personally enjoy the cutting aspect, nor, frankly the feeling of bleeding out. Anyone who's suffered a dramatic loss in blood pressure can tell you it's a very unpleasant sensation that can lead to panic and confusion.
Finally, I'd feel sorry for whomever it was who found my body and/or had to clean up the mess. The human body holds a LOT of blood.
If you're dead set on it (if you'll pardon the pun) I would advise adding a large amount of Rivotril (klonopin) to the Zopiclone as extra insurance against waking up.