Not the G40 Savant that others on this site are, but at the bare minimum, throwing in the Pacific board means you’re going to have to deal with Japan somehow. That puts additional strain on the US Economy, which means you’re going to have a tougher time bringing a critical mass of US/UK Navy to bear in the Atlantic. You can’t just send 100% of USA’s income after the Europe map or Japan will win on the Pacific map with minimal difficulty (UK Pacific and Australia are pathetically weak without US Support).
Additionally, you don’t get the free Russian INF that you do in E40 anymore, so that’s going to result in your Russian stack being a bit weaker.