If we're being pedantic... There is only one JRC, which is the JRC4558D present in both the OD808 and Drivetrain. Because of this, I agree with the above that it's the rest of the circuit, not the IC that makes more of a difference. I don't mean to knock the modded Tubescreamers, I'm sure they do sound better than stock, in the same way that if I took my car to Star Performance to get all the major components uprated, it would be a better car. The question is will it be cost efficient? As we both seem to agree that the original tube screamer circuit has been surpassed, all I am suggesting is that there is an alternative to a man with a soldering iron. Tube screamers command a price premium on name alone, when other more well sorted TS clones (such as the Voodoo Labs Sparkle Drive, The Reverend Drivetrain and The Visual Sound V2 Route 808) don't. You might save some cash selling and buying on ebay, as I did. P.S. Before anyone mentions authenticity, any new tubescreamer (not made by Maxon) is technically a copy.