With SMF you won't be able to integrate well. They run as 2 separate sites, and it's almost impossible to get it to work anymore. I used to have it running, and it died, and I gave up
Check the plugin repository, here's one thing it lists
http://wordpress.org/extend/plugins/wpforum/But search the pkugins for forum because there's other stuff there
edit--just read your post more closely. With those plugins, the forum runs within wordpress. If you don't care about any integration at all, then you can do whatever.
I use SMF and dig it. Have about 100 users on it. Never had any problems. Things is, it's totally outside of wordpress. You install it in a different directory or subdomain...it's styled separately, uses different database, etc
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