I've found them to be fine. The breakup isn't quite as smooth as the JRC4558, but other than that they sound good to my ear. I've done numerous repairs with the TI version and no complaints.
things are goin okay. barely played any guitar over the past 6 months or so but have some friends who are getting going and it's revived my interest for the time being.
was mainly asking hot tubes in terms of the "are they any better than stock production units?" question. it's not like any op amp is necessarily craptastic (unless you are thinking in audiophile terms like signal to noise ratio), but some can do what you want while others can't.
DD's are smoother with more gain/dirt and less "boost" feel.
D's are harsher with more bite. less gain but more "boost" feel.
imo, DD's are a lot friendlier in solid state setups (less ear gouge). D's are better for note definition and a lot of attack but practically require a tube amp.
not really a question of better, more a question of "better suited for."