I'm against everyone having a full copy of the forum for a range of reasons. As a scare tactic I can mention you will go from 1~2 guys keeping a secret to everyone accessing private forums (yes MMX had those), to maybe even accounts & PMs depending on how SMF stores things. But more honestly, people have treated the handbooks with respect and their open access also keeps the reason to repost them on your favorite forum down, but when it comes to copying an entire forum you can ban someone and they can turn around and repost the forum, with extras, and promise better moderation/uptime/bot-&-adfree/whatever to draw users. Heck, then can even create a method to merge and continue to populate their copy with any new thread submitted in the original on top of their own exclusive discussions, wouldn't that make you feel like you're missing out? Finally you run into pretty much the same problem we have with MMX, not everyone can access the information in a readable way and it's pretty spotty what someone else has put back online.
Instead, why not create a user-sided back-to-BB-code button? That'll allow people to instantly obtain the original formatting off cache sites for reposts. Then of course we can try to put people in charge up creating an archive. Obviously some quality control would be great and a lengthy discussion that'll draw some extremes but we the MMF can take it on our selves as a community project to mirror decent handbooks into a single zip/rar file.