Thanks, John. That means a lot coming from you. I've come a long way and I still have much further to go!
Great to hear you got a 25! It's a little different than the 21, but I don't dislike any of the differences at all. The 25 is like a combination of the Umnumzaan and the 21, along with a couple of slight improvements that have been made overall.
Pluses for the 25:
The 25 has thicker blade stock than the 21, coming to 4mm, and instead of the deep hollow grind that the 21 has, it has a wide-wheel hollow grind. This means that the grind is still a hollow grind, but has a much shallower radius in the blade, sitting between a hollow and a flat grind. I'll try and include the picture from CRK's website (click to enlarge):
View attachment 514192
The balde is a mixture of the 21 blade shape and the old bull-nose shape that previous reeve knives have had, like the Classic Sebenza, and it's predecessors (don't remember all the names).
The 25 also has a traditional pivot system, allowing for the pivot to be tightened down to udjust action, instead of the bushing system. At first, I wasn't sure I liked this option, and when breaking in the knife, you may have a tendency to under-tighten the knife because it will still feel a little stiff when at the adjustment level it should be. After use, I was much more comfortable with the traditional pivot than the bushing system. This is mainly because it is one lese part in the knife, and like I said, I have had to take the knfie down in a hunting tent

It also makes the knife less likely to have issues with the action if exposed to water in my experience. The bushin give one more place watter can get in, while the traditional pivot has just one surface (this likely won't ever matter to the majority of owners).
The 25 also has a braoder pivot, and larger-diameter washers, as well as the holes in the washers to lock in grease (though the newer 21's I think have that as well).
The frame also has no hole in it.
Minuses:
The pivot tales a different size tool to adjust and take down than the rest of the knife in the 25, while it does not in the 21.
It is a little (tiny) bit heavier, so if weight is a SUPER issue, something to keep in mind.
No dedicated lanyard hole/pin. The rear standoff is used to mount a lanyard, which would be a neutral comment, except that the lanyard can come into contact with the edge of the blade on accasion, so I don't put one on as it slowly chews up the lanyard.
The 25 currently only comes in either the standard hanles or the Micarta inlays (which are hard to find). I would imagine that we will see more inlays as time goes on, but it leaves much fewer choices for people right now.
The 25 DOES require locktite. The screws are not made to be interference-fit like the 21, so you will need to use loctite to secure the screws unless you are okay with adjusting them frequently. They include a tube of purple loctite in the box for the 25, so you don't have to worry, but if you play on having the knife anywhere around heavier vibrations (for whatever reason), then use blue.
Neutral:
The knife handle has been designed with additional groves for grip. They fit my hands fine, but not perfectly, so I imagine that's a personal thing.
The access to the lockbar is much less significant. It is still not hard by any means to access for me, and it helps the grip of the knife in my opinion, but some people may not like it.
The hanldle has an overall narrower profile. Some poeple will prefer it, some people like the height of the 21. This also includes the handle getting wider at the rear, starting at the second finger choil. The 21 has a much more coffin-styled handle, while the 25 tapers down towards the from until the 2 finger choils, and then thickens out profoundly around the pivot.
*Phew*, Hope I got everything