[Jawed]

  IEMs are definately an aquired experience, and some don't adapt.  I have small ear canals, and there are only a few non-custom IEMs that I can wear for more than 20 minutes or so.
 
Now CUSTOM IEMs are a completely different story.  A mid level custom (~800-1000 USD) should provide at least the quality of the HD650s (I have 650s and custom IEMs myself)
 
You might spend some time on the forum investigating the various IEMs from the multitude of providers, and find someone's description that matches the sound signature that you like.  I have previously used Etymotic ER4, which was uncomfortable when pushed in for a seal well enough to coax some bass out of them.  I still use the Ety ER6i for working out.  It was when I got the Ultimate Ears UE-10pro that my eyes got opened on both the comfort and the increased fidelity you get with custom IEMs.  Several years later I have the JH Audio JH13pro, that I currently use.  Neither of these is quite as warm as the HD650s, but much more accurate and detailed.  There are bass heavy IEMs that you may prefer, I loved the HD650s when I started this journey many years ago, but the HD800s are my regular cans at the office.  I use either my JH13s or a pair of AT ESW9JPN when I am traveling and use my computer.  JH13s with iPad for music or movies on planes.
 
There are also some companies that have both universal fit and custom fit with the same drivers and crossovers that you might could try before getting the custom made.  An expensive version at Ultimate Ears actually lets you tailer the sound on a device before you actually get them made, and the sound signature is what you have chosen.

 
Are you saying there are companies that literally offer demo units, or merely that they sell universals and customs with the same basic sound?

 

[billybob_jcv]

Any BA universal can be reshelled into a custom, if you are willing to pay to get it done.

 

[SteveHiFi]

 
Fi-BA-SS - your comment about the cable should apply equally to the Heaven series shouldn't it? If not, why is the Heaven series less fragile?
 
SE846 - I've read about the filters - they don't appear to offer the option I want: "less analytical". To be honest I'm cagey about rejecting this as the performance level does seem to be genuinely high. I'm not against neutral, just wary of something that is described primarily as accurate rather than intensely communicative.

The Heaven series have a ribbon-type cable which feels a lot stronger, the FI-BA-SS is thin but I've not read about any issues with it - it's just a bit weedy looking.
 
When I tried the SE846 I got the impression of either crystal clear clarity with the white filters, or the idea I was missing something with the other filters, but there's no accounting for taste.
 
If you can make it to us near Worthing, we have a few of these models which you can try - SE846, IE800, the Heavens (the 7 and 8 are in and out a bit for reviews but likely) and a couple more in that price range.

 

[Jawed]

Any BA universal can be reshelled into a custom, if you are willing to pay to get it done.

I suspect that those units where the shape/internal construction/filling material/body material are an intrinsic part of the acoustic design prolly won't work so well.
 
It was interesting reading early thoughts about the Final Audio Fi-BA-SS because there was a widespread assumption that BA style units can't be affected by the sealing of the body. The small vents on the rear of the body had quite a few people calling shenanigans. Quickly silenced by those who experimented by covering up those holes.

 

[Jawed]

I've posted a new thread with my impressions from a long dem I did at HiFi Headphones yesterday:

http://www.head-fi.org/t/747482/hifi-headphones-uk-dem-dita-final-sennheiser-shure

Thanks very much Steve for you help yesterday