Thanks for the reply, the above quote sums up where I'm at right now. The trouble is, I found the EPH-100 to be so good that I'm a little worried I could be disappointed with any CIEM I get. Before I purchased the EPH-100 I had been trying another single driver IEM that was nearly three times the price, but it did not have anywhere near as much detail as the EPH-100. I would be quite happy to stick with the Yams, but there are situations where I need better isolation and I know the only solution for that is a ZPM. I haven't read Average_Joe's review so I'll see if I can find it. Meanwhile, any direct comparisons to the EPH-100 would be gratefully received, especially with regards to clarity.
Edit: lol... ZPM - I'll leave that in there - I meant CIEM, (It's been a long day... and guess what show I'm watching
Here's a link to average_joe's report: http://www.head-fi.org/t/599349/acs-t1-live-custom-iem-review-silicone-for-the-big-stage.
I moved up to the ACS T1 from Ultimate Ears Triple Fi 10s. I posted a comparison of the two here in case it also helps: http://www.head-fi.org/t/477897/acs-t1-custom-review-and-impressions-thread/255#post_8984568.
Best of luck with the decision making.