Yes, I have. The Samba is crisper, brighter, and drier overall compared to the Flamenco with both switches down. The bass response is the only region where this differs, where the Flamenco is brighter and airier in tonality and neutral in impact, while the Samba's sub-bass is much more pronounced, and mid-bass more dark.
They both have transparent and clear midranges that are closer to neutral than natural. I can't recall how they differ in this region specifically, but it's worth noting that they both have a midrange that's airy and articulate, but rather "small" if that makes sense; although it's technically proficient, it's not the most soulful, or euphonic, or rich midrange. Though, with the bass switch up, the Flamenco has a rather hefty lower midrange that compensates for this at the cost of a bit of coherence.
The upper-midrange of the Samba is significantly more pronounced, leading to the impression of more clarity and air, but this causes the Samba to become a more fatiguing IEM than the Flamenco when heard at the same listening volumes. The Flamenco's upper midrange and treble can somewhat simulate this with the treble switch up, but there's a certain hardness to the Samba's treble that's not present even in this configuration; the Flamenco will always come out smoother. However, due to the Flamenco's superior extension, resolution, instrument placement and instrument body on the Flamenco supercede that of the Samba.
Soundstage-wise, they both present engaging, proportionate, and rather intimate soundstages, compared to the competition. Although, great imaging and stage organisation prevents its soundscape from ever becoming congested, closed-in, or messy. The Samba has the airier presentation with (arguably) a blacker background, while the Flamenco's superior extension and instrument reproduction presents a stabler image with a more realistic and "physical" aural image.
I haven't heard the IQ, so I can't comment, but the W900 is definitely quite different to both. It's significantly wider and more natural-sounding; coming back to my VE8-vs-Zeus comparison, the Jomo's sound more like uber-transparent studio monitors, while the W900 is beautifully life-like; listening to acoustic music on the W900 is a pure joy! However, the W900's treble is a definite sore spot. It is gorgeously-extended, but lacks sparkle and air, both of which the Jomo's definitely do not lack. As a result, the W900 sounds incoherent up-top, and lacks a bit of articulation, thought that will aid in naturalness nonetheless. The W900's dynamic bass is a clear stand-out in this comparison, though some may find it lacks air and speed in its decay compared to the two BA-based IEMs, so it probably won't be the most ideal choice if you listen to metal and prog-rock. It's impact and extension on the other hand, are pretty friggin' great for my tastes 
The A18 is still the better, and most of all, more impressive monitor. In terms of resolution the ES80 is similar, but the A18 has an even wider stage, and fuller sound. Bigger notes and vocals. Its bass isn't technically better, because the ES80's really excels in its neutral role. But its just bigger in terms of impact, making it more engaging. Its upper mids and treble are brighter; while this makes the ES80's signature slightly more coherent, it gives the A18 an extra touch of excitement, while making it more upfront in its detail retrieval. So the ES80 is more neutral, and you could say its bass and treble are more 'correct'; but there's no denying the A18 sounds more engaging.
