More playing around with these things. The way that they distort is not as smooth as regular vacuum tubes, it's rougher and rattier. They sound very nice clean, but even when clean if you're boosting them with a pedal the gritty characteristic seems to come back. They work great if you just get distortion from a pedal and use the amp clean.
For my uses, (due to the gritty character) I don't like them in V1 or V2 positions at all. Sticking one in the PI position however, slightly changes the feel of the amp to be a bit tighter and noticeably reduces hiss/noise. I kinda like them here, both the blue (seemingly more headroom) and the yellow (about as much headroom as the regular 12ax7) . . . with one caveat . . . which is that while they work very well at low to medium volumes, when you fully open the amp up to get some power tube distortion something sounds a bit off . . . and there's a touch of that grittiness that you hear with the RVs in the preamp tubes coming back.
Overall they're still kinda cool, I just don't like the gritty character for soul, blues, funk, or jazz. Will probably keep one in the PI while playing around the house, but swap it out when playing out.