Im having some heavy problems with the converter as well. The first time it looked to go well but after the members which said unfinished a message came telling me that the converter had stopped to prevent an overloading of my server but when I would click continue it would start where it stopped. I clicked continue however this did not help, the converter did not continue at all yet ended up in an endless loading of the page untill it simple continued for ages. I check the database in phpMyAdmin yet it had the exact same values, the converter was stuck.
After cleaning the database, installing a fresh SMF I tried the converter again. This time however it didnt even do the members ! I cleaned all cookies and stuff.
In fact the endless loading caused my server to automatically go offline for a while. Now this has nothing to do with the server itself as its a pretty heavy one.
The forum im trying to convert has more then 40.000 members and around 90.000 posts. The database is about 200MB. I know this is quite heavy for a script but it should be able to handle it shouldnt it ?