As for why the LSC forums are slow, not really sure. Most of us are here too. If I have a specific Lonestar question, I start there, and usually get a good response. However, if it is a general cobra question, I start here.
A guess as to why the LSC forums are slow - just a guess - perhaps they've had a few slow months/years so maybe there aren't as many current builds going on. Again, just a guess. They may have had the best three years in their history...
When I built mine from 2010-2012, I was always on, asking questions or searching - and always got a good response. Lots of archived information there.
I usually check there once a week or so, but like you said, not much going on right now.
And, I agree with what has been said. I would not hesitate to buy their kit. The extra leg room is great. They recently "redesigned" their kit, going over everything, improving the quality and fitment. It's apparently a much easier build now that when I did mine. They call the new body style a 427GT instead of the LS427.