You'd be on the edge wouldn't you?
Not sure what you're talking about with the (CGI?) flash irc bit but I feet the need to relay the fact that they'll frown on persistent connection and shut them down in a hurry if they're found, and if it's in use much at all, it would likely be found.
In use much also begs other questions, I don't believe they'd kick you for using you alloted bandwidth, they're extremely honest when it comes to doing what they say (and beyond usually, tho bandwidth overages have a cost associated).
However if you're seeing that much traffic with forums and chat, odds are you're going to be hitting the processor more than "your fair share". Unfortunately there's currently no hard guidelines to allow you to know about this and prevent it. You just wake up one day and have an email saying your sites been moved to an evaluation server so you can trim your CPU useage befoer you're tossed or moved to dedicated service, your choice.
That's happened to me recently and it's been an excellent experience. I consider wht they've done to accomodate my account that was unfarily sucking resources, to be way above and beyond the call of duty and or terms of service.
Dreamhost is a class outfit but you have to look at your stuff real hard.
I think you'd have a difficult time finding a better shared host for features and integrity.
check this thread for my eval server banter:
edit: "Also, how is your up time?" about missed that one... I have more than a few sites here (spread across several physical machines) and have not experienced any downtime of significant nature for a year at least (whenever the big DDoS attack happened, been a while). I have noticed, like you, people complaining of downtime, but these complaints seem to coincide with the big promotional sale that's been drawing new customers like flies. So it's either growth issues (which they historically sort pretty quickly) or just the fact that there's an exponential number of n00bs on board that are quicker to freak out, no telling which.