[kyrnel]

It was the "Find:" code that was wrong for forumdisplay.php, not the replacement code.

Basically how it works is this:
When you pass the userid to the cache_ordered_forums() function it adds the field [subscribeforumid] to the query. If this field is populated with a value, then that means that you are subscribed to that forum. So it doesnt add any queries, but it makes an existing query slightly more complex.

So it will work with existing subscriptions. No need to update anything.