I think you have just discovered the folly of buying a heavy hitter as your first (?) (...and only?) double rifle. Doubles in the medium calibres (9.3 to .400) are sweet-shooting lively hunting rifles which are a genuine pleasure to carry and hunt with. They are marvellous killers and make great general hunting rifles for medium game, at least in my neck of the woods. Many of us hunt with double rifles by preference. I rarely use bolt-guns these days, preferring doubles up to .577 for everything, and I am neither wealthy nor a fool, thanks.

Buying one big double, for the reasons you hint at, and then letting it hurt you, won't make you an expert on the use of doubles for hunting IMHO. Get that .450 out in the field and belt a few hogs or deer in the river bottoms, and you will soon appreciate the virtues of a double rifle for hunting. Better still, stop fooling yourself. Trade it on a medium calibre double and start enjoying your shooting again.