In my opinion, 470NE is a good choice, a versatile cartridge, you can shot wild boar's and elefant's, and it's not a too big problem to buy factory load's! The problem is your budget! HEYM made good double's in old english tradition, but not cheap, you have to paye about 15000 Euros. The Chapuis are good double's in French tradition of St.Etienne's gunmaker's, and are a little bit cheaper. Merkel are good one's, but rather in smaller caliber's like 9,3x74R for exemple. Krieghoff in big calibers are, in my opinion, a compromise, the action is to small and they look not very nice. For this reason, they are very cheap!