Thanks for all the replies! I've got mine now, and so far am very impressed. I love the way the battery lasts all day (no more swapping out with the charger several times a day). I also see that the button really is a well made, durable mechanical switch with a decent sized hunk of metal for its pin -- with the mini, I went through a lot of batteries, mostly because the automatic switch went out (either not coming on, or simply staying on). I did accidently disconnect the button once, but got it back on and learn a lesson about being careful about torquing it so it screws off.
Really, it seems to me that the SD does for the battery what the eGo C now does for the atty -- allows the battery itself to be replaced, not the whole battery as with the mini or eGo. That rocks, and if they last like some people say, great. Some of my assumptions about the number of batteries I need, based on the mini seem to be obsolete now. (I have tons to mini attys, though, those actually do last me a while.)
I'm not sure all ever have a huge collection like some people, but maybe an extra for work or as "one for the road" some day :-/
P.S.: People who still like the term "electronic cigarette" would need a new one for the SD, since its really much closer to a high-tech pipe than a cigarette -- that how if feels to me, I think of it as my cyborg pipe