I did a lot of research before buying the SXS I have. Asked many questions and did a lot of reading on a couple of the forums that have a lot of people with some knowledge of double guns. That research led me to buying one with the confidence of being able to get what I wanted. And I did. I was considering two guns at first. One smallbore, one bigbore. I've decided not to pursue the bigbore, simply because I don't need it, I am not going hunting griz or going to Africa.
I wanted rimmed cartridges, wanted some versatility. A 7x57R or a 7x65R or an 8x57JRS is a great choice for over here, the 9.3x74R was not what I wanted, I have a #1 in 450/400NE 3", the 9.3 just seemed to be too close to it to bother with. I could get 30-06 or 300WM, but, they are not rimmed.
But, I wanted something in that range of cartridge. Found out about the 30R Blaser (7.62x68R), did some research on it, ordered one. It filled the bill quite nicely, decent velocities, good bullet selection.
Brass is a bit tougher to come by, but, could be had, ammo is avail in Canada. Reloading info takes some searching, but, it is out there, and, I have all that I could get, which ended up being a fair amount.
I like that it is an uncommon cartridge, I like the way it performs too. It's not as cheap to shoot as others, but, still a bunch cheaper than the NE cartridges. I have had a lot of fun with it so far, the one limiting factor of a SXS may be some longer shots, but, they can be worked around also. The O/U is a better choice in that regard, but, it isn't my choice of gun (It'd be too easy). Even here in Alberta, and in BC, I've shot 95% of my animals under 200 yds, and the SXS in 30R or the 6.5's, 7mm's, 8mm's and the 9.3x74R are fine within that range. The learning experience on shooting the SXS is well worth the time spent on it, it is a lot of fun.
I'm burning sawdust on the thought of a 6.5x57R, or similar, the thought kinda turns my crank.