I'm not sure when this change was made as it's been a little while since I really dived into looking at grinders, but sometime within the last few years Herb Ripper put out what I think is one of the most innovative designs for a 4-piece grinder to date.
Instead of the traditional 4 pieces with 2 threaded sections, they've significantly reduced the overall size of the grinder by essentially combining the material collection and kief chambers into one. By creating a drop-in receptacle for the ground material that slots into the section that holds the kief, they're able to maintain a 4-piece design that's basically the same size as their 3-piece unit. Apologies if this is old news and for the uneven gif:
Here are some assembled comparison pics beside the v1. I haven't measured, but the holding capacity feels similar as well. The new model is on the left, v1 on the right in both pics. First is a comparison between the two 4-piece configurations:
This second pic shows the v1 in the 3 piece configuration, and it's very close in size. The new model is only about 0.5cm taller, maybe slightly less than that.
Seems like an obvious solution in retrospect, and I assume it also carries the benefit of using fewer raw materials in the construction potentially reducing machining time and is also lighter and easier to use while maintaining the same functionality for the end user. The one complaint I did have about the v1 Ripper and by extension I assume this applies to all all stainless steel models regardless of brand is that they're a little on the heavy side, especially compared to their aluminum counterparts. Having a smaller, lighter unit that has the same functionality and similar capacity is a significant change and is definitely a big plus that isn't necessarily apparent just by looking at it in pictures, IMO.
I also had some concerns about the grind itself as they don't seem to offer any thing other than what looks to be the equivalent of their old medium plate now. I think I'd still go for a coarse plate option if they offered one, but the current one has been working well with my vapes.
I go back and forth as to whether or not kief collecting is worthwhile. On the one hand, I've never been actually able to find a really good use that would justify the additional effort of collecting it. Years ago, I found some promising leads with edibles that I initially thought might pan out, but I learned that I don't have the ability to metabolize THC through my digestive system, so personally that was a dead-end that I stopped pursuing. Garnishing my session for an extra kick is about the best use case I've been able to find and I do like that on occasion, but I don't know if it's worth specifically seeking out a 4-piece grinder just for that purpose.
On the other hand, I don't think collecting kief actually makes any appreciable difference to the end user per session. This is by no means definitive as there are way too many variables to account for, but I generally see it this way: I took an 0.5g nugget and ran it through the newer Herb Ripper pictured above right after a fresh cleaning. For my usage, this amount was enough for one Flowerpot bowl (~2 CH spoon scoops), one Tornado bowl (~2 scoops), one Anvil bowl (~1 scoop) and a about half what I usually use with my injectors (just a touch less than 1 scoop).
This was the total kief produced:
After collecting it and trying to separate it into 4 roughly even piles, it looks like this:
If you divide it out equally and put the same amount into each of the bowls, I don't think I would be able to feel a noticeable difference. Even with the entire pile in a single bowl, I'm skeptical that I'd feel anything extra. I think the question of whether or not collecting kief is worthwhile ultimately comes down to your individual preferences, but I also don't think it takes away anything significant if you do.