I had to look up Ddrt, lol. I haven't seen too many folks using that on here, but that doesn't mean no one is using it. Using 2 ropes with 2 separate anchor points might get a little excessive, probably more for arborists, but I could be wrong. Most folks use SRT, which is what I did last year as my primary climbing method for presets. I love it and will definitely keep the system and use it a bunch.
YES to your first question, SRT is awesome, when done correctly it can be extremely quiet and quick. I would skip the micro pulley and the webbing foot loop, just get some accessory cord and tie one, thats what I did and it works just fine. I used a separate tether but you certainly don't need to do that, although sometimes the SRT line isn't in the best location for your tether and it's nice to have the option but I think you could certainly get by without it.
The toughest part about Ddrt, I think, again I've never done it, I think would be getting your line setup in the tree, I think you would have to get a friction saver or something similar for the rope to smoothly move as you climb, because the rope moves as you climb right?
Anyway, hopefully, that helps, I'm not real sure I fully understand the Ddrt stuff, good luck, some useful links below. Maybe one of our other SRT pro's can chime in.
I've got more info and links in a newbie write-up I did a while back to consolidate info.
http://saddlehunter.com/community/index.php?threads/noobie-advice-info.5590/#post-76917
Ddrt and SRT
http://treebuzz.com/pdf/CC_Jun07.pdf
RADS/Yo-Yo Explained
http://www.newtribe.com/documents/tip4.htm
How to install and remove the rope, great video, helped me a lot when I got started.