I've never been fortunate enough to handle a 700 NE double but I have no doubt they're big and heavy.
A week or so back I received a gift from a client who hunted with me last year.
The gift was a 700 NE cartridge for my collection.
I've owned a 600 NE cartridge for over 20 years and have seen and handled a 700 round before, but honestly you tend to forget just how huge they really are!
The difference in appearence between 577 and 600 is not all that great, but from 600 to 700 is massive!