Ryan, I own the X10s and I can say that for plane travel isolation, I have yet to have any of my (limited range of) IEMs best them. For me, the X10s have superior isolation when stationary (as on a plane). Thus, I don't think it's too unusual that the 232 isn't satisfying your dead-silence craving in the air. I also note that for a single BA, the X10s have plenty of bass, with impact and rumble and what have you.
Given your situation, I should say I'm no expert on the PFE232, I've only heard the 112 and yes, it was closer to neutral than my collection is. I'm sure (and also I've read around the place) that the 232 is a super capable IEM with great precision and quality bass, but for some people that just doesn't do it.
I also own the Sennheiser IE80s, and let me say, I find them an upgrade from the X10s in every way except isolation, including bass quality (and quantity, if you so choose). The rumble on these things with my humble E11 amp's bass boost is more than satisfactory, and with EDM it's great. As for treble detail and resolution, as well as reproducing a 'natural' sound, you will find they do not perform up to PFE232 standard (based entirely on impressions I've read, as I don't own the 232). I still think the IE80 has a smooth, pretty detailed, non-sibilant treble and, to my ears, wonderfully rich mids like those on my Momentum, which I like.
At $270 from amazon.de, I think the IE80s are a worthwhile 'downgrade' if you like bass and choose to let go of your 232s. Except the isolation with stock tips is poor at best - buy some foam tips from Comply or Jaben or wherever you can source them, and you should be set. The ergonomics of the IE80s can be tricky with some people, so make sure you are prepared to return them to Amazon... All the way in Germany... Or audition them somewhere before buying.
Or... you could always give your 232s to me and we can swap! Just kidding :D