Dilemma...

So, this often happens to me.  I'll be trucking along with a story, and all of a sudden, out of the blue, a new, fantastic, wonderful idea comes to me.  And the new idea always feels so much more interesting and so much better than the one I'm working on.

And that's what happened this weekend.

I've been working steadily on my NaNo project and feel good about my word count so far.  I'm not 100% enthralled with my story, but I'm doing something really different and challenging for this one, so that's probably why.  Then bam!  Saturday night, I had the most amazingly awesome idea for a new book.  The character's voice is so clear in my head, even though he hasn't given me his name yet (yes, this one's going to be a boy POV), and I'm just itching to dive in.

I have a dilemma on my hands.  Do I keep going with the project I'm about a third of the way into, or do I scrap that for the moment and move on to this new, more interesting idea?

I feel like I should hold off on the new one because there is likely to be quite a bit of research I need to do, but I often write first and research later so I can toss the details in when I revise.  So that's kind of a lame excuse not to get writing.  But I also hate to leave things unfinished....

Has this ever happened to you?