The A7 plus a prime (it's a prime and an adapter in that shot) is a lot smaller than a 5D + a prime.
Just buy one.
What I ditched...
5D, Canon 20-35mm, 70-300mm. Sigma 20mm f1.8, 50mm f1.4, 85mm f1,4, 150mm f2.8, 12-24mm.
Yes, WYSIWYG, the in view histogram, peaking, zebras and the magnified view are all attractive features. Even with my G1 I am much more likely get a difficult lighting shot first time without blowing the highlights or blocking the shadows up too much than with the 5D as with a conventional DSLR you have to guess how much compensation to dial in and then check the shot and reshoot if necessary. That palava has pretty much disappeared now for me. In very difficult situations I might have to take a shot twice... but in such difficult lighting with the 5D I'd have to take more shots chimping and deleting as I go.