Just a comment:
This one doesnt run properly if the database is relatively big.
I converted a Snitz to SMF today, but did lots of work manually.
First, I tried running in my personal computer locally.
It always screws the processor for about 10-20 minutes, then it prints "Converting posts (this may take time...)" but it actually exits the code. Because its trimmed. (For example no continue button)
Then I uploaded to the production server, the same result.
The database was only 20 Megs..
It doesnt continue from where it left. The reason I think; these new convert.php files divide the sum of data into parts proportional to its size. For example divides 1000 messages into 100 parts and inserts the data 100 by 100.
But if the database goes over 10000-20000 posts, it divides to for example 1500 and cant insert it once. Suppose that its 50.000 messages, it will probably lock the server completely.