Hi Immortal,
I've heard the EX1000 quite a few times, and I own the XBA-4. You mention in your first post that you'd like thumping bass. The EX1000 are very capable, natural sounding IEM's but I can tell you they are not really at all about 'thumping bass'. If you listen to a lot of modern recordings, particularly pop music, the overall balance of the EX1000 may be a bit tiring to listen to after a while because the sound is a tad lean. You may want to consider the EX800ST / MDR7550. While I only heard this model once, it is a bit more neutral than the EX1000 but has a similar character. I do not know if you are using this for portable use, but the EX1000's design does not particularly lend itself well to portable use because of its lack of isolation and potential wind noise.
Related to the earlier question, I would choose the EX1000 over the SE535 if the keyword was natural. The SE535 has a very mellow sound but the BA sounded a little off/tacky to me compared to the dynamic driver in the EX1000. The sub-bass response of the SE535 was also relatively poor.
The XBA-4 is absolutely a fun and engaging listen, though it has not attracted a great reputation in the forums in its relatively short life so far. I can tell you that the bass is very solid and articulate, and soundstaging is startlingly pin-point accurate in terms of placing. The one issue is that the highs have an almost metallic, shimmery timbre to them. They aren't tremendously sibilant to my ears, but they don't sound entirely natural. You can tone down the treble by using the included foam hybrid tips, though I prefer the sound of the normal silicones. I find isolation to be great. I like the XBA-4 overall, especially for modern pop recordings. It's gotten an oddly bad rap here on Head Fi but the Amazon Japan price /group buy puts it at a very interesting pricepoint.
Another darkhorse option I can recommend which hasn't been mentioned before, but based on your desire for thumping bass: The Atrio M5 with MG7 drivers. It's much cheaper than the other options being discussed here, but it is a surprisingly capable IEM with the most startling sub-bass response I have ever heard in any piece of portable audio gear. They are also quite isolating.