The 805 is a VERY well built rifle, indeed. For 99% of civilian uses, it is just fine, indeed. The changes were from a military standpoint, for ease of use in a battlefield environment,being lighter and of course, the bolt release..in two places. I don't carry my BREN many places other than the range, and it usually rides in a case, so the weight doesn't become an issue, not being a grunt in the field. I might be a wee bit tired if I take her hunting with me, but that's why I also have the excellent CZ military 3 point sling, too.
I don't know about durability, because the 805 really hasn't had any noted long term issues I am aware of, while the BREN 2 is no new there hasn't been time for any issues to crop up. I would have to assume made with CZ toughness and quality that both rifles will keep on working long after I am done.
The only thing that could negatively impact the BREN 805 is the lack of spare parts as the firearm is discontinued, but since they are still in service, in the Czech Army as second line, if nothing else, so spare parts will most likely be available for some time.
The last cool thing is - they are orphans. They were only imported into the US for about 2 years. While not really RARE, they are far more limited numbers than many other "service" grade rifles. I had a buddy of mine watch me shoot my BREN 805 a month or so ago, and when I mentioned that being an FDE BREN 805 it's a relatively uncommon rifle, he wanted to know why I was shooting my collectors item! Is aid, "Is rifle. Is to be shot."
Long story short, go for it, grab one - you won't be disappointed