I'm with Zen' on this, I'm thinking that the edginess is not being produced by the caps, and the culprit is to be found elsewhere.
Hang onto those caps Ozcal, and see if you can find the real criminal!
Edit:Oops...didn't see ya' post mate
I have some Chinese Mil' surplus caps in my amp and have thought them a bit too veiled and dark, was going to replace them soon, but found that the hookup wire I used to connect them was the offender (1mm copper...what was I thinking!), change it to 24 gauge Neotech copper and I have my detail back!