Welcome to the small world when you start using forums. Everything appears just a click away.
You will soon find that what you once thought may well be far from the truth. Eg while you may well think you have the most stringent laws in the UK you will find it interesting to know you are far from the truth. There are far worse.
To answer a couple of your questions. The reason that some rifles are called BRNO and some CZ is because they are just that. They are different makes. BRNO is not CZ and CZ is definitely not BRNO. Just have a look at your two, the model five is BRNO and the 2EH is CZ. I could agree that they look slightly similar but as you can now see they really are quite different. In fact they are really a lot different from each other.
As to the model five being rare. Rare is only ever a relative term and I certainly would not call them rare when compared to some of the other BRNOs. I do only have two model fives but that?s by choice, there are plenty to be had. Once you have been around the forums a little then you may call ?rare? such models that were only ever made in small runs. What I?m talking about is runs of around 70 total. Or even perhaps the larger runs of 500 or 1000 total. I have several rifles that fall into these categories. Yet these are still only relatively rare to others. I have several that are almost unheard of and in fact many people have never heard or seen them at all. Transition models showing features of both past and future models are often sometimes what you could call ?rare?.
I hope you don?t mind me chipping in. I guess I don?t fall into your ?cousin? category as I assume that across the ?Big Pond? is usually into the USA from you guys and also I fail on another important point, I?m not particularly religious. I would be among the first to support your choice to be though, if that counts for anything?