I really dislike forums where I have to visit the web page to read all replies. I far prefer getting all the replies to my mailbox and I can open up the thread's page if there's anything I need to reply to.
Also note that it will Soon™ be possible to reply to topics by replying to your mail notification of it, and may even become possible to start new topics by sending an e-mail to the forum.
But yeah, I have no advice to add that hasn't already been offered. Try playing around with digest settings and report back here if you find something that works for you.