As I analyse the subject, I would explain this lack of reviews with the following two points:
- The European market is probably the biggest for unicycling. Although there are lots of great riders in America, it seems that we have way more here in Europe.
- The European market is shared between Mad4One and Qu-ax high-end unicycles. We don’t see many new KH unis here.
I may be wrong, but I think not a lot of KH unis have been sold in the last year - so, the lack of reviews. They are more expensive than their counterparts - at least, in Europe -, but they don’t offer much more. Sure, their bearing caps are way better than RGB’s or Mad4One’s, but who really cares? 200€ are a lot for better bearing caps.
BTW, this 2023 lineup does not offer a lot of new things, compared to what already existed on the market. I mean, KH Boundary hubs are just Qu-ax Qaxle hubs painted in black. Left brake tabs are great, but they have existed on other frames for a decade. Boundary cranks are probably the most important new things on the market, as they offer a decent q-factor for riders who like q-factor - I do, for extreme muni, as I feel more stable but haven’t taken the time to give them a try, yet.
I don’t mean KH unis are bad - on the contrary, they are amazing for stock unis -, but they don’t differ much from the other contenders. So, they aren’t bought 
If I were you, I’d choose the RGB. IMHO, it has the best value for money. Oracle unis are great, but a bit too heavy for me. As I have said previously, KHs are quite pricey in Europe based on what they offer compared to other brands.
RGBs, on the other hand, are light and way less expensive than KHs.
On the RGB topic: as they are light, they don’t have the solidest frames. They’re great for XC and touring, but they can twist if they take a hard fall. So, I wouldn’t recommend them for extreme DH.