ScT IRC is the most active, u r right, similar to their irc is blackcats irc, believe it or not too
ScT forum is one of the most active forums but you must consider torrentbytes forums too which is pretty active (regardless that TB users database is 3x that of sct) but both forums are serious anyway (i.e, no spam forums there to just increase # of posts), I haven't seen its forum but I've read that it's also very active
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