Maybe what Tim is bringing up about the 100T lacking 'weight and depth' compared to the SB300 is precisely one of the things I love about it. I had a hard time for years learning that what I was hearing onstage, especially frequencies below say 100 Hz., had nothing to do with what the audience was hearing. This was especially true during the 70's when I used a Sunn folded 18 along with a Sunn 215. If I was hearing the bottom end I liked onstage, it was rattling people's teeth 20' and further from the stage. In the mid 80's when I switched to 2x410 Hartkes and a GK800RB, it still felt thin to me onstage when I got it dialed in so it wasn't too bottom heavy out in the room. I'm not sure what it is about the 100T/410Neo combo, but it sounds much rounder and fuller to me onstage, though I've never had complaints from audience or soundmen about too much low end. Whenever I've allowed another bass player to sit in, what I hear out front is pretty much exactly what I'm hearing onstage.
I don't know if this has anything to do with anything. I don't know if the power tubes going into self-compression at relatively low volume is helping keep the low end in check, or if the output transformer just naturally rolls off sub-lows, or if it's a combination of those. But I do know I haven't had to fight the mud like I used to.