Freight Train, that would be great if I liked it even more than I do already. I have to say that your review and updates was a big factor in picking this amp up, and I see that we're coming from similar places tone-wise.
My thought in terms of the 100t vs high-watt micro head thing is that it's very hard to compare the two, as they are coming from completely different design philosophies. In my opinion, you want the 100t to start breaking up in the power section, as that's where a lot of the tone is, getting that musical distortion. A 100t is going to sound much better at 8 on the master then a micro (or any solid state) is at eight. So really I think you've got much more usable range in the 100, even though the total range of the 100 might be a fair bit less. Also from what I've read, it takes 10 times the power to get twice as loud, so a 900 watt head MIGHT get twice as loud, but again once it's up there, I'm thinking the tone isn't there. Plus there's so many other factors that could effect headroom that I won't even try to pretend I'm an expert in figuring it out.
There are obviously down sides to the 100t, it's easily six times the weight of some of the micros out there, and I can imagine tubes are fairly pricy to replace. But really I think Fender nailed it out of the park with this one. They've taken a vintage-style tone stack, added a modern channel, plus you've got self-biasing tubes, 100/25/silent modes, a great DI out, etc. if you're willing to accept the limitations and issues inherent with a tube amp, you really can't go wrong with this one.
As for me, like I stated in a previous post, I've been playing mostly Markbass stuff prior to picking up the 100t. If I was an upright player, or maybe playing some jazz or whatnot, I think I'd rather play the MB stuff. But since I'm pretty much an old-school rock type player, this is my amp. That said, I may at some point pick up a micro, just for a backup, and the times I don't want to lug the Fender around. We bass players are really living in a golden age where average bass players with average incomes can rock world class gear.