I think you meant the 1601s? (bolded text). Whenever I speak of the 160Xs, I'm always referring to both the 1601s & 1602s (aka the PFs). I don't find the 1601s to be technically superior to the 1602s, and, FWIW, I find myself reaching more often for my 1602s as, to this day, I'm still surprised at how they manage to grab my ears, heart & body in ways my HD800s, K3003s. 1601SS & FI-BA-SS don't (for some of the music I listen to), hence why I still "need" these unique IEMs. Now, the 1601SS, while very, very close sonically, has a tad more airiness which I think might make me choose them over the 1602SS, but only in the scenario I described in my previous posts ("If I had to choose only one...and X & Y phones did not exist..."), ie while SQ-wise the 1601SS is definitely not placed in the middle between the FI-BA-SS & 1602SS, the 1601SS is just a tad less idiosyncratic / unapologetic, which would allow me to enjoy a bit more music with them.
Like you, a lot of the classical music I listen to has been recorded in the 60s, 70s & 80s, though I tend to listen more to chamber & solo music than orchestral / symphonic works. But, no matter what subgenres of classical music, I don't personally find the FI-BA-SS "distracting" and, in fact, it's precisely with orchestral works that I tend (though not always) to prefer them over the 160Xs.
I'm curious about the 1p2, yes, but not that curious, really (more curious about the Parterre and, to a lesser extent, the much cheaper SonicDiver SD2). Apart from a couple of non-SQ aspects that don't appeal to me much, the 1p2's midrange descriptions by several people make me think I might not be fully convinced as I'm someone who craves and values a good / solid midrange a great deal. Also, my impression is that, although the 1p2 has been hyped quite a bit mostly by a couple of members, the actual sonic differences between it and the K3003s are not as marked as some claim (let's not forget the K3003s have been rather maligned by 2-3 people who, in turn, have been instrumental in the parroting / regurgitating we've seen for quite some time by other members [the so-called incoherence & treble peaks issues mostly]. FWIW, one member who hardly ever posts on the 1p2 thread owned—not just auditioned—both IEMs and decided to keep the AKGs).
As noted a while ago, I'd really love to try the SR-009 (and also the SR-007 Mk I & II), but that won't be happening in the foreseeable future (unless perhaps one day one of my trips to the UK happens to coincide with a HF UK meet…). I honestly wonder, though, whether my ears would tell me that any of those Stax phones would be a marked sonic upgrade over the HD800s to warrant a possible purchase, all the more considering the huge price difference between the Senns & the Stax.