Hello Pitbull1:
I had the same question as you did, and after seeing both models side by side, I ended up buying both. ATCF and Sebenza are very good knives and each has its distinct characteristics and advantages.
Both units lock up was very solid. I have my ATCF's liner lock recess so that the meaty part of my fingers won't interfere the lock when employing a white knuckle grip. Sebenza won't encounter that problem due to its frame lock design. If you're looking for brute strength it's hard to beat Sebenza at any price. Some forum members have compared the Sebenza to a foldable fix blade - I can't agree more.
With respect to ergonomic, ATCF is the clear winner. My Ti handle profile is very thin. The handle feels very secure using reserve or normal grip. The action is silky smooth. What's more, Terzuola uses Teflon washer so it never needs oil - (another plus becuase it doesn't collect dust or lint) In addition, the ball detent of all Terzuola knives are among the best I've encountered. In fact, I have no reservation about carrying my ATCF in a tip up fashion because I know if will not open unintentionally. I have heard rumors of Sebenza opening up inadvertently. The thought of that is a bit disconcerting.
Sebenza's BG-42 definitely tops ATCF ATS-34. If I am not mistaken, Terzuola only offers his knives in ATS-34.
Blade Geometry: Sebenza is more efficient cutter to it thinner profile; however, the down side is that it is more susceptible to chipping along the edge. I do, however, prefer the thicker profile of the ATCF. It looks more agressive and has a thicker blade tip.
Looks: They both have very clean lines and are very classy. I give the edge to ATCF.
Even though my ATCF is my daily carry for the past one and a half year. If I had to choose between ATCF or Sebenza, I'd give a slight edge to Sebenza just because it's build like a tank. You can't go wrong with either one. Your best bet is compare both knives side by side.
[This message has been edited by Bob Litt (edited 09-27-2000).]