It certainly will be a classic NE cartridge in the future.

Why:
1. It is being offered by a number of manufacturers in modern rifles which are affordable - Kriefhof, Merkel, Searcy, probably others;
2. Loaded cartridges and brass can be obtained;
3. Projectiles are very easily obtained in comparison to many other double rifle calibres - similar to a .450 (.458) and a .470;
4. It uses a consistent bore - .416 - unlike the other very fine .400's - it does not have a problem in the bore size could vary between .408 and .411.;
5. The calibre matches a popular bolt action bore size - .416 Rigby and .416 Rem Mag;
6. The calibre sounds right, a .500/.416 Nitro Express". It sounds like a older NE round and a classic. Non of these "Ultras", "Magnums" etc and even worse a brand-name in its title. It is a 'open' to all calibre.

I aim to purchase one one day in a modern side-by-side setup with a scope. Just to be different from the other(s).