I've not checked alta in awhile for file type support. I know you can find sht, shtm, shtml, asp, and cgi filetypes on alta, but what are their real status? Are they rankings killers like they used to be?
I have had limited success getting database driven pages indexed. I was mainly just seeing if I could get url's with a ? indexed at all. I was successful at getting them indexed but none of the pages ranked well.
My problem was that the content changed so often that all I could really optimize was the meta info. I eventually decided to concetrate more on the non dynamic sections of the site, and haven't had the time to do any follow up testing yet.
Bret, I agree 23 in 20000 is not many, but to get true result of your test you would need to know the average ratio of shtml pages to all others on the net and then compare the two. If there were only lets say 10 shtml pages for every 10000 other pages then the conclusion might be totally different.