*work in progress* My Evaluation Methods // Glossary of Terms I Use // FR Graphs for Newbs

[Inks]

All I can recall as a weakness in the RE272 was narrow soundspace, which was clearly in the RE252 as well.  Everything else was pretty exceptional, I didn't mind the light bass, it was high quality and much better than heavy bass which only gives me temporary tinnitus.
 
If you think the CKM500 was bloated down low, I'll skip that then I think.  In my view the CKW1000ANV is closer to FI-BA-SS and farther from GR07, that should give you an indication.  The CKM1000 is apparently the 'brighter' model and close to the CKM99 sound.

The RE272 has good soundstage IMO, just insert it very shallow, I use big Monster supertips for this, to get both isolation and a good seal via shallow insertion. With shallow insertion treble is very airy as is soundstage. I agree, the bass is of high quality, though IMO, I sometimes need more of it, just a bit. 
 
CKM99 was a disaster IMO.