Max number of Taxonomies?

with 5-10 you see absolutely no difference. With proper performance tuning on both drupal and server end you can achieve very good performance with very large number of taxonomy.

For your question please define " a ton or taxonomies".

Thanks, I just wanted a sanity check about having 5-10 taxonomies per node.

However for curiosity (and potential future dev) I was wondering if there was a best practices upper bound or if someone had experience with a project that had 20-50 taxonomies per node.

My question would have to be, why WOULD you need that many taxonomies? Performance aside, which as litwol said, isn't a major issue on a properly tuned server, I'm more concerned with the business rules that would dictated 50 taxonomy vocabularies. Is it possible that you just don't have enough content types on your site where you could break things down a bit more logically in that way? Theming CCK types is relatively easy, and assuming that you're already using the same template, or are at least planning to do so, you can probably get away with copying a few files in your theme layer to save you a lot of headache down the road. Leveraging logical breaks, such as content types, as opposed to relying on taxonomy for everything is a more elegant solution.

Mike