There are tons (because volume of reviews is measured in metric tons LOL) of formal reviews online so I'm going to save you the grief from reading through the nitty gritty and give you my abbreviated $0.02 in notes form:
-Good build, feel like good quality
-Gave me all the cables I needed, but then I'm not testing them with the Nikon Speedlites (whereupon I believe I would need an adapter that I'm missing... I might find it in my Gadget Infinity boxes)
-Syncs at 1/250th with my D3 and AB800's. There will be a long-term confirmation of this. But so far so good?
-Ridiculous distances. Stood as far away as I could in my backyard (maybe about 60 yards) and shot through a window/wall and the strobes still fired. Will be long-term confirmation on this too.
-Dip switches NOT that difficult to read. I already memorized them and I'm no genius. First 4 set the channel (16 combinations), next two (5 and 6) set the groups (A is both down, B is 5 up 6 down, C is 5 down 6 up). Switch 7 is something about outputting more comprehensive data output for diagnostics or something of that nature. Switch 8 is for the modeling lamp.
-Transmitter knobs are awesome. And no, they're not confusing enough to have to label them. Or maybe I'm just not shooting far enough to ever get confused.
-Yup they control the power settings on the AlienBees. This is SOOOO going to save me a ton of time with my setups. I can't believe PCB (Paul C. Buff) doesn't have a version of these triggers! This is part of the reason I opted for these and not the Cyber Commander because I don't need something so complicated as the Cyber Commander, yet I need something that's reliable, has great range, and small/lower profile.
-CR123 batteries suck. I'm getting rechargeables. Perhaps my biggest gripe.
-No mounting point for the receivers to the ABs. Went with velcro. I hate velcro... well I don't "hate" velcro but I used as little as possible and stuck them to the side of the ABs with the antenna pointing backwards (to the camera most of the time). Actually stuck it to the sticker that says "AB800" on the AB800. Even if the receiver falls off (if it unsticks from the velcro) it's still attached via the telephone cord RJ-45 (I think).
-Still can't believe the yardage on this thing. Stupid long.
-There's an on/off on both the transmitter/receiver. There's no on/off on the transmitter for the Cactus (Gadget Infinity) V4.
-There's no locking mechanism on the transmitter. Slightly annoying but not too much really.
-Modeling lamps still work with the receiver which is nice :)
-There's an internal battery test that tells you how much juice is left in the battery. I believe this feature is on both the transmitter and receiver.
At the end of the day these things are tools. To be used. The better they work, the more I can focus on shooting and not worrying about reliability and technology. That means I need to figure out what the long-term success rate is? Realistically the Gadget Infinity Cactus V4 were triggering at about 96-98%. There certainly were shoots where they did not misfire at all. But there were some shoots where they would misfire inexplicably... and those were the times that stick out in my mind and proved most frustrating of all. I am hoping beyond hope that the RP JrX will outshine the Cactus triggers in that respect.
That being said, I'm in no hurry to get rid of the Cactus V4. They might prove to be a valuable backup someday that I need another unit/system if for some reason the RP JrX aren't working or whatever. I can't imagine a situation that might occur. I'm hoping that doesn't ever happen. But I like options. And a backup is always welcome.
Do I care about HSS (high-speed sync)? No. I have read that they don't do HSS. If you want HSS, get the PX system from RP.
As I've stated earlier, I didn't want the Cyber Commander from PCB because maybe I'm just a low-tech kind of guy? Or maybe I don't like change? What I know for sure is that I like knobs and it's a lot easier and faster to turn a knob to set a power output than it is to fiddle around with the Cyber Commander. I don't need ratios because I hardly if ever use my light meter as it stands! I sure as hell don't have the need to control 12 or 16 channels different lights. It really is a shame that PCB CyberSyncs can't control the power outputs on the ABs. Gotta tip my hat to RP for doing that even though they're not part of PCB.
Another important questions is: How long will the batteries last? My V4 were very stingy with power and almost never ran out of batteries in all the time that I've used them. I don't think I've ever changed the battery on the transmitter. I believe it uses a small flat battery though (I have a spare that's sitting in my camera bag). I might have changed one set of AAA's on the V4 receiver. I have heard that the RP JrX's are not that stingy on power but we'll find out over time.
Over all, I'm pleased with the triggers/receivers. Let's see what happens in the field...