DeepDot web has Zion on a pathetic 53% uptime and DNStats doesn't have them listed (guess that was waived not really a must have then) and everytime I vistit the site it's down.
Superlist qualifications states:
You must demonstrate at least 80% uptime during the one month wait period. Get in touch with dnstats.net before you post your announcement, so your market gets listed on there and the uptime gets monitored.
Everyone else appears to have worked around the DDoS problem by rotating address or load balance their hidden services.
Zion though...
Works fine for me. 100 percent uptime these last few weeks