I have been using vBulletin since 2002 and suffered using the built-in search engine for several years until I wrote my own search engine. The search engine I wrote searches directly on the post and thread tables to find what users are looking for. This has worked amazingly well for over four years on my forum.
My forum has over 1 million posts and this direct search technique works very quickly. I encourage xenForo to take a close look at using a simple SELECT statement that directly searchers the post and thread tables.
The benefit of using the MySQL SELECT directly on the post and thread tables is that any word or character can be searched. For example you can search for:
xenForo is a better forum
By not limiting the search engine, users can quickly find the information they are looking for.
Thank you for your consideration on this.