Mechanics of Bumps and Upvotes?

I'd like to ask some questions about the general design direction of the Community Beta, with regard to thread visibility.

On the current LoL forum, upvotes have no effect on visibility (though a thread can be downvote-closed) and a bump moves the thread to the top of the forum.

On Reddit, comments have no effect on visibility and no thread, no matter how upvoted or active, will last more than a few days due to karma decay.

What about Community Beta?

(1) Will comments boost visibility of a thread? Or only upvotes?

(2) Will there be a harsh karma decay system?

My personal view is that there should be some sort of balance here. Reddit is a news/link-sharing site; this is a discussion site. I think it's important that active, popular threads be able to stay relatively visible.

I'd propose:

(1) Comments should boost thread visibility, but repeated posts from the same person should have diminishing impacts on thread visibility.

(2) New threads should have "novelty karma" that decays with time, but a thread's overall karma should not. New threads will tend to be toward the top, but long-running well-upvoted threads should be able to compete with hot new threads.

I think a pure Reddit-style system would not only be redundant with r/lol (and it's not totally clear which would win out in a fight to the death) but would do some damage to the LoL community. For example, take Factions. At last count, nearly half of Factions players learned about Factions because they saw the sign-up thread bumped when someone else signed up. (People post to the sign-up thread to confirm ownership of the Summoner name they just entered into the GDoc form.) And of course, there are also long-running skin request threads (like Surprise Party Fiddlesticks) and rework input threads. These would never be possible on a Reddit-style system.

For all these reasons, I think it would be better for Community Beta to adopt a more discussion forum approach rather than just imitating Reddit.

I'd be curious to know more about the comment/upvote visibility mechanics currently in place and those that are being considered.