Don't have an R8 but own a couple of R93 stock/receiver units and a half-dozen barrels. I'm amazed to realize that I've been into the system for about 12 years now. In practical terms, I don't think I have ever used a better hunting rifle; accuracy, trigger, handling, comfort...no downfalls in any of these areas.a I've sold or traded off a couple of barrels in the past, but only because of changing needs and tastes; I have never had a Blaser barrel that was not an outstanding shooter.
I was first drawn to the gun because of how innovative and different its operating system was at the time. The superfast straight pull operating system is obviously no longer a novelty to me, but I like it as much now as I did then. I love the de-cocking safety, and am continually impressed by the wonderful QD Blaser scope mounts. I still smile when I take the scope off the rifle, then remove the barrel from the receiver...and re-assemble with no perceptible change in POI. Thing is, after 10+ years of having this work so well...I still don't trust it to work the next time. When I put the gun together I still insist upon a shot or two to confirm what I already know, i.e. that it's still sighted in. I don't travel much for hunting anymore so that's less of a thing nowadays in any case. Incidentally, one of the few nits I might pick with the Blaser system is the need for a thankfully-standard Allen key to remove and replace the barrel. lt's not the end of the world, easy to keep one on your keychain or whatever, but some of the newer makers standing on Blaser's shoulders to create the ultimate hunting rifle now allow for completely tool-less takedown.
It's worth noting that, while you can have two or more scopes pre-sighted-in for your barrel and know that they are both ready to go instantly...that doesn't mean that you can swap the scope instantly from one barrel to another and expect it to work. Not only will sighting-in be obviously required, but the QD mounts usually need to be adjusted to each individual barrel to achieve the correct tension. Switching the mount to another barrel isn't typically lightning quick. If you take a couple of barrels halfway around the world, plan on separate scope(s) for each barrel. And if you lose the insanely razor-thin but still fairly wide Blaser flat-blade driver that is required to adjust the scope mounts...good luck finding another one anywhere other than a Blaser dealer.
I appreciate the shorter overall length of the rifle as opposed to a more traditional bolt rifle. The Blaser puts the magazine right up above the trigger instead of in front of it, which shaves a couple inches off overall length.
All of the above features of the R93 are shared by the newer R-8. The big difference is the easily-removable trigger/magazine unit in the R8. I don't find this particularly attractive, but I'm a dinosaur who still hunts happily with hinged floorplates or blind magazines. YMMV. The other change to the R8 is that it is slightly heftier and more massive, which I take as a negative. This more substantial build lets it accept chamberings all the way up into the big .400's, whereas the R93 topped out at "only" .416Rem. I can live with that, especially when it gives me a lighter, livelier rifle.
They are great travel rifles. I don't think of them as legitimate takedowns, since removing the barrel still leaves you with a package the length of the complete riflestock. A true takedown, IMHO, needs to come apart in the middle to make for the shortest possible package...but the Blaser system, alone or with an extra barrel and/or a couple of scopes, does fit into a very short case that doesn't scream "I have a gun!" which is nice to have when you are towing it around behind you in some foreign airport where you already stick out like a cockroach on a wedding cake.
If you can look at pictures of Blasers R-series rifles...especially some of the newer variants...and think "Wow! That's gorgeous!"...then you're lucky. I personally think that the basic Professional or Offroad versions...plain black synthetic stock, matte-blued...are very business-like and serious in appearance. But the harder that Blaser tries to dress up their guns...IMHO...the uglier and more tasteless they get. I bought them and keep them despite the visuals, not because of them. Again, to each his own.
As I get older and continue paring down my rifle collection, the Blaser system just looks better and better to me, as a choice for the one-for-everything mentality. I don't know if I will ever get to the point where they are all I have, but they will certainly be among the last guns I would sell.