I like it when someone dares to be different :P

I think WR would have the whole rimless ejector thing pretty down packed for reliability - they built that .425 WR DOUBLE for a maharajah, so one just assume it would be a tiger/leopard/ele gun too? That's a rebated rim, not just rimless.
Of course I have no experience with doubles, and no idea how reliably the aforementioned gun is. I just assume a big name like WR wouldn't let sub-performance leave the shop.

Another thing: if I was totally rich and got a new double rifle made it would be a .700 by H&H, so my taste in doubles is questionable

Edit again: 500Boswell - was that one of the ones made by that home machinist fellow? Also built a .577 Tyrannosaur double?