A few thoughts from an unbiased new member....
The value of forums that have been around for years - even if they decline in activity or membership - is the rich history of useful information that can easily be found by both old and new members. Ie. jetting suggestions, which pipe is best, dynographs, pictures, ignition timing curves, standard modifications, etc.
In starting up a new forum as much as defected members would like to move forward with new cutting-edge information, there is value in making sure you have the basics available to attract new and retain old membership - and ensure that your site is a good one stop shop for all things R.
My suggestion to the defected members (who no longer want or can contribute information on other sites and want to make this site is the primary source for 250R information) would be to review useful information that you may have shared previously and consider creating new posts here that include a refresh of the "old" information you may have posted elsewhere. Sometimes that can even create new discussion that refreshes an old topic.
I have some dynographs and other information that I can post and refresh here to this site - presuming that folks here agree such information is useful.