I might as well add my 2 cents to the debate.
My view on replying to threads is that it's totally up to the reader. If you live in the expectation of never getting a reply, then your expectations are never disappointed.
Yes, it is nice to have engagement in your threads, but it's not a given. The key thing is to share things that make you happy, and worry not about the engagement.
I must admit, Mr Green and Mr Karlos, you go above and beyond with your replying to threads. I hope it's not too time consuming for you. And if it starts to feel like a job then you know something is going wrong (this is where I realized World of Warcraft wasn't working for me, it was like a job, every day have to log in and club some baby seals to death to get some gold coin for the latest pair of bestest evar magical underpants.)
Sometimes I'm busy/away/simply can't be arsed. And I reserve the right to be a lazy c^nt!
Kind regards,
Cuthbert