19 in GD, 4554 total, registered 1/4/2000. (Just shy of being a 99er!)
I think OP meant fewest number of posts.
Registered 1/2/2003.
16 posts in GD out of 4,422 total posts. (0.36%)
Which surprised me because I didn’t think I had ever posted in GD, but it looks like my most recent GD post was in Feb 2011. So I guess it has been a while.
I’ve got 94 in great debates. Yeah, that doesn’t really put me in the running since my overall post count is only 3,949. (3950 including this one.)
4 out of 3,834
08-21-2006
1 out of 1,412. That gosh darned thread was moved there afterwards!
But I’m fairly new here…since June 2013.
2/1400 since March 2003.
And I’m pretty sure both of those started in CS or GQ.
I’m clearly not in the running, but I think it’s interesting that of my 29 posts in GD, 24 of them were in my first three years, and only 5 have occurred since 2009.
(Joined July 2006, 3,688 posts including this one.)
June 1999
59 posts in GD
This post will be my 16584th post. I signed up December 23, 1999. I’ve posted 111 times in Great Debates.
Joined in August 2010
Just over 1000 posts
0 posts in GD
Joined 07-02-2009.
Total Posts 20,653
445 posts in GD.
Not an obvious winner, however they’ve all been quality posts.
Joined 2-24-2004 (albeit I didn’t become a regular poster until last year).
44 of 2,344 posts.
So not the champ, but in the mix.
Registered in Oct 2000. 11000+ posts.
5 posts in GD, pretty sure one of them MPSIMS before it was moved to GD
Joined 2-1-2006
42 posts.
4 in GD.
13 out of 1785 posts in GD. (0.7%)
Joined July 6, 2001
There’s no purchase required, right?
You don’t explicitly state that to be the case, and they usually do mention it. 
0 out of 41 posts in GD. (0.00%)
Joined 11/1/2004.
Joined June 2000.
19/6773 posts in GD.
I’m surprised the number is that high. Even more surprising I *started *some GD threads back in the day.
Not my favorite forum.
I’m there! Do you extend credit?