We've been down this road and suggest you might want to use ActiveForums rather than the DNN Forum Module. There are a number of operative factors in implementation and user experience, but the main one is that the native forums don't have search in the industry standard sense. When you do a search for more than one word it requires an exact match of those words contiguously, which is worlds away from true information retrieval such as one expects and finds almost everywhere else. Imagine searching for
President Mexico
in Google, and it would only return pages with that exactly, and not, for example: President of Mexico
If you use ActiveForums they support proper information retrieval search, not just string match.
There are a numbe of other factors weighing in this direction including a big difference in apparent speed, and, importantly, that the native forums implements its own private messaging. The latter modularizes improperly so that if you use private messaging elsewhere in your site the two private messaging systems won't be integrated!. This problem is anticipated and avoided in ActiveForums insofar as they integrate cleanly with MyMessages using a simple tag.