First time I've ever seen efficient and a Nosler cartridge mentioned together!If you're going to get another 7mm (280AI is a great round). Why not looking into something a little more efficient say a 28 Nosler or a 7PRC. Something that will let you take advantage of the heavy 7mm bullets.
If you are looking for a need, you have it cover with what's in your possession. If you have an itch...only one fix.