I've owned the Bose Triport OE for a while now. I am pretty happy with it, but I admit it's not perfect. But I love it because it is a mix of superb comfort, good sound and that warm, bassy sound that I love.
I am no audiophile but I do collect headphones/earphones and like to have different sets to really enjoy my music. I just wanted to put in my opinion on this discussion.
Having also had the PX100s, I can't believe ANYONE would compare the PX100s to the OE's. There is absolutely no comparison. They don't even sound close. If I am looking for something that sounds like the Bose OE, and you are telling me I can get better sound but with the same quality of bass as the OE but with tighter Sound Quality all aruond, the PX100 doesn't even begin to cut it. The PX100 has excellent highs and mids and is a very bright phone, it sounds great but the bass is not there. You can hear some of it but there is no detail on the low end, and it doesn't have that warm all-encompassing bass feel. At all.
On the other hand, the Vibe Duo. This one is a set that I *can* recommend as a substitute for the Bose. I have it as well, actually I have the Vibes, but the duo is pretty much the same thing except with some minor enhancements and phone control. It's about half the price of the Bose, but the sound signature is quite comparable, and in many ways better. First off, the Vibes have a better soundstage than the Triports by a large margin. Second, the highs and mids are better pronounce, and 'sparkle' more than on the Bose. They aren't quite as comfortable as IE's, but they are still pretty comfy. Just nowhere near as comfy as the Bose Triport OE. Lastly, and most importantly, the bass is very tight. It has that warm, oozing bass that I love. Not as heavy as on the Triports but still there and very engaging. In some ways this is better, and you might prefer that level of bass. But I personally prefer the bass on the Triports. In addition, the overall sound signature of the Vibes feels "metallic" for lack of a better term. It is very energetic and alive. The Bose signature overall though is "airy" and "wooden," it is very laidback and free floating, with a powerful bass grounding. But overall the two are very comparable and the Vmoda Vibes are a great alternative for the Bose.
Now, I am about to buy a K81DJ. The reason being that I am expanding my horizons. AKG is a well-regarded audiophile brand, so I wanted to really compare the Triport OEs (which audiophiles hate) to some phones that are similar and well regarded. The K81DJs are not audiophile-quality phones, they are said to have a good bass response and are not the most natural, nor are they reference quality, but that sounds similar to the Bose Triport OE's, and audiophiles still recommend the K81DJs/K518DJs. So I will be picking them up later, they are less than half the price of the Triport OE's, and pitting the two against each other should give me additional insight to sound, I am sure.
People claim the K81Djs are better than the OE in every way except comfort, and that the bass on it is bass done right; still powerful, just the way I like it, but with better quality and control and less boominess. This should teach me a few things about how to appreciate sound, so this should be a great purchase. I was originally planning to get maybe the K142HD or the K271 Mk II but I heard the sound on those is really flat and boring, and I might regret the purchase, even if they are audiophile level. They probably also don't compare directly to the Bose OE.