I think the 6v T1 is available in the original version (2 core, 30W) and the special order version (3 core, ?W). The other special order T1 that Tim mentioned is a 3.7V single center core low voltage version.
I've been training myself mostly with my 6v T1 base powering a DART core with PG lately, and I've found that I can preheat for 10 seconds, then take a BIG hit, continue to hold the power switch on for the 10 seconds I hold in the first hit, then take the second hit, turning the power off half way into the second hit, and for more hits after that, I just power up 5 seconds before the hit, drop power half way through the hit, and turn the power back on 5 seconds before I want to take the next hit. repeat.
This won't hold true when I switch from oil-in-the-ceramic mode with PG to herb in the Evo/T1 though. I've been able to see exactly what's going on with the oil vaping by removing the mouthpiece from the DART and just watching down the core for the vapor to appear. With the Evo (or the T1) with herb, no real vapor will appear until you take a hit, as air being drawn through the core is necessary with herb. So it will have to be the "test puff" method to tell, which removes (a little) heat from the core every time.
I'm making my best guess as to what form of generation one TV stuff I want once the line is dead and version two stuff is available. I suspect TV will recore anything from generation one you want, as long as they have parts, but I've been putting off sending Zeki my cores the past month, and I think I'm going to do it next week, after the hurricane passes, before it's too late.
In any case, I've still subjected myself to carrying around a bag of batteries when I want to vape herb (as opposed to PG)...
Oh, and I agree that different strains/cures of herb require different technique. One batch of NYC Diesel I have is so "moist" that I've taken to leaving a little out on a piece of paper overnight before I use it in the Evo or T1. Too much wasted effort and battery life is required to get it going when it's that moist.