No.
I don't like to be notified about anything non-critical. I take time in my day to check the 'threads' link at the top of Hacker News and spend the 10 seconds or so it takes me to see if anyone has replied to anything I posted over the past few days and if I feel it warrants a response.
If it does I pop a note in my to-do list along with a link to the comment in question and get around to it later.
The last thing I want is yet another ping to tell me someone replied to me on a social news site. One of the reasons I comment on Hacker News is that it doesn't poke me in the eye for every reply I may get.
Honestly if Hacker News were to add this feature I would disable it instantly or maybe just not bother interacting with the community if they did it in an invasive way that I cannot disable, although that is quite unlikely.
Quick edit: I didn't mean for the above to sound hostile to what you have made. Apologies if it comes across that way. I just feel very strongly about over-notifications in todays world. For those that want it hopefully they find your extension helpful!