A well-known, large software company has recently opened a development office in my hometown. I really like the company, and if I wanted to work for a large software company - this one would be my top choice. However, I am not really looking for a position like this at the moment - I am quite happy with my current work arrangement.
I received an email from a technical recruiter at the company inviting me to participate in a "recruiting event" for the company. From the email, I (mis)understood this to be something along the lines of an information session / meet-and-greet with the team, with multiple candidates present at once. They asked for my resume (which I provided), and then asked me to complete a coding question online (I thought this was a bit strange for screening people for a simple info-session, but I did complete it). I now got an invitation for a full interview loop, something that I definitely wasn't expecting.
I am torn whether I should take the interview or not. I am pretty sure I won't take the job now if offered (unless the offer is unreasonably good I suppose : ), but I definitely don't want to burn any bridges since, as I said, I really like this company and can definitely see myself wanting the job 6/12/24 months down the road. I am also concerned that I may not be able to dedicate the appropriate time to prepare for a tough technical interview given my current work commitments.
So: To maximize my chances with this company in the future, should I take the interview right now or politely decline? If decline, how should I phrase the reason for doing so? If I take the interview, get the offer and then decline it, how will it reflect on me if I'll seek employment with the same company (and specifically the same exact small group within the company) in the future?
NOTE: I found a similar question here, but it's not a duplicate. My main question is about how my different courses of actions (take interview/decline offer vs decline interview) will affect my future employability with the very same company (and the very same group within the company). The other question doesn't address this at all.