My first Sebenza was a small regular back in the late 90s. Fast forward to this last year and I picked up my first Large 21, and also my first Large Regular. I've been fortunate enough to spend some time with each and here's my thoughts. Overall Looks. Visually, it's a tradeoff between the Regular and 21. I prefer the scalloping of the Regular to the smooth lines of the 21, but it's mainly aesthetic. While I imagine it's possible to feel the scalloping during extreme heavy repetitive use, I can't tell on casual use. If I was using the knife to cut for hours each day, I might feel a difference and perhaps the smoother 21 might be preferred. But with casual use, it's down to aesthetics and I prefer the Regular here. Blade steel. The regular is BG42 and my 21 is S30V. I don't believe the casual user will be able to tell the difference. If you're sharpening your knife weekly, then maybe the softer S30V or S35VN is easier to resharpen. To me, this is a wash for my purposes. The only issue for me is if I wind up breaking the Regular blade, I can't currently get a replacement, whereas 21s can have the blade replaced. CRK is working on Regular blade replacements in the future. Slight nod to the 21 for the ability to replace the blade, but it's so slight I call it a wash since I've never broken a knife blade in my life. Lock mechanism. Many people have a problem with BG42 regulars exhibiting lock stick. My current user has little to no lock stick. I'm not sure of the technical reason for the lock stick and how the 21 has reduced this phenomenon. For me it's a wash since they are the same in my models, but I understand many others do have lock stick so I give the slight nod to the 21. Fasteners. The Regulars and early 21s have single sided fasteners. The new 21s have two sided fasteners. This change was made because people were lock-titing their fasteners in place and had to be drilled out. However, most people, including myself, significantly prefer the old style single sided fasteners. Perhaps I'm doing it wrong, but the new fasteners are really difficult to use. With the single sided, I can use a hex key to undo one side, and then push through the hole with the hex key to pop out the other piece (flat side). With the two sided fasteners, the hex key just pushes through the second fastener's hex hole. And then I really have to finagle that second fastener out. I give the strong favor to the Regular here (assuming single sided fasteners). Washers. The Regulars have solid washers and new 21s have perforated washers. I've tried both, and the solid washers seem significantly better. Regular wins here. Handle Shape. The Regular has a convex handle on the backside whereas the 21 has a concave. I recall Photoman in one of his review views making comment that the 21 was a better fit for his hand. I'd leave this up to personal preference and personally, I can't feel a difference. It's a wash for me. Pocket Clip. The new style 21 pocket clip seems superior to the old style flat clip in terms of function, although the Regular clip is aesthetically more pleasing to me. Since we're talking users, I'd give the nod here to the 21, however the pocket clips are backwards compatible and easily available so while the nod goes to the 21, I call it a wash since for a few dollars you can change the clip on the regular. Blade shape. There's some minor differences between the two blades. The one that immediately stands out to me is that the grind of the bottom of the blade is deeper in the 21, such that it extends down under the handle scale. I am not sure functionally why this change was made and it looks a little nicer on the 21 but not much. I am ignorant of the overall changes to the blade but from my layman's opinion, it's a wash. Overall. I am somewhat disappointed with the 21. It's a fantastic knife and I love mine, but it seems like a step backwards from the Regular. I don't plan to get rid of my 21s, primarily because they are half the price of Regulars (on the secondary market), and if I break or lose one, it's less of a big deal. Also, while I do prefer the Regular on an overall net basis, it's only slight, maybe 10% better. So it's not that I hate the 21, just that I am disappointed that CRK seems to have moved backwards. Perhaps these changes were made as a cost savings measure in some cases. For example, the Regular has a tiny detail that around the entire back side of scale, there is 2 to 3 thin parallel lines milled for visual appeal. The 21 lacks this feature. It's purely aesthetic and most wouldn't notice it, but it seems like it adds extra machining costs to the piece, which is likely why it was removed. For anyone who doesn't own a regular, I highly suggest looking for one on the for sale forum. Consider an S30V model which are generally a bit lower cost than the BG42 models.