Just got new equipment today. Was supposed to be a hopper 3 and 4K Joey and Wireless Joey.
Was told the 4K Joey was trash and pointless so stay away from it. Had to move to a wired Joey4 instead which requires you to have a hopper Plus on your account. They did not connect it because I didn't want it but had to add it to my account for the Joey 4 to live there. Then they were going to give me a wireless Joey for but they didn't have one on the truck so I kept my existing Wireless Joey. A joey 4 would not work with a hopper 3 without the Plus box being activated on my account.
Joey 4's will work without the plus. The will bring it out, and may force the install, but it can be removed and everything will work fine. A good installer will help you uninstall it, or perhaps just leave it off.
There are advantages and disadvantages of the plus. All of the apps are android versions, and will enable 4K HDR on YouTube for one example.
The biggest current downside, is that the plus will not support multi-view/PIP.
That may change soon because those features are planned for Joey 4 as well.
The other issue is that the Joey4 and the plus always output 4K, and flag that as HDR, even for SDR content unless you disable enhanced HDMI on your TV.
The problem with that is that your picture settings on the TV generally should be adjusted differently for HDR content. (Typically different brightness i.e. 100% for HDR, and possibly different color settings as well.)
This is not a huge problem, but when I watch using the Joey, I normally leave HDMI set to standard, and ONLY change that setting to enhanced when watching HDR content.