I have mine in a eco/sand mixture, and they seem to be doing well, no barbel damage that I can see. It seems like eco has changed, the bags I bought 2 years ago had softer granules, this new stuff they are putting out looks scary!
I kept sids & striatas on eco, they're much more "diggish" than my kuhlis ever were. No problems. My kuhlis, both black & striped, were never diggers even on very fine pool sand. Go for it!