Sorry I'm a bit late. I had a date last night with a very demanding schedule.
Bass 1 is .... the Fender. Strung with some flats of unknown origin that were on my G-Bass when I bought it. I didn't like the flats on the G-Bass, but I do really like them on the Fender.
Bass 2 is the Yamaha BB415 strung with brand new TI Jazz flats (with just the P pickup soloed).
There are 2 things that I really think are interesting that I've gotten out of this poll.
1) The Fender American Standard Precision is THE Gold Standard for a Precision-style bass (duh). The closeness in voting in the poll really speaks well (to me, anyway) of what a good job Yamaha has done with the BB415.
One person has already pointed out that my Fender having a Warmoth neck means that it's not really a Fender and doesn't sound like a real Fender Precision. My response to that is that I reckon if it's as hard to distinguish my Fendermoth from the Yamaha as this poll indicates, then I think it would be nigh-on impossible to tell the difference between my Fendermoth and a "real" Fender in a blind test. Unfortunately, I don't have a '62 AV RI with a maple board laying around to use to prove that.
2) There were 3 responses in this thread that indicated which bass they thought sounded better, regardless of which one is the Fender. All 3 responses said they thought Bass 2 (the Yamaha) sounded better (to them, obviously).
I'm surprised also that the Yamaha even fooled flewis, who actually built my Fendermoth.
My personal conclusion: A few months ago, I was really on a quest for a 5-string version of my Fendermoth. I.e. a passive 5-string with a P pickup, and, maybe a J pickup, too. I even started a thread about it and nobody ever mentioned the Yamaha as an option. I ended up getting an MPG Level 5 and love it. But, now I think I can safely say that the Yamaha is a really, really nice option for anybody that is in the same boat I was. And the regular price on the Yamaha, through MF, etc. was only $450! So, used ones are out there now pretty regularly in the $300 range. I just don't think you can beat that (if you want a passive PJ 5'er, anyway).