200 f2- nothing prepares you for how heavy and awkward that thing is. No way I would carry it around a wedding, and wouldn't be too excited about taking it along on an engagement shoot. It felt so unbalanced on the d800.
Yeah, a 200/f2 will be unbalanced on a non-pro body without a vertical grip. Put the 200/f2 on a 1 series body and you will notice a big difference (much more balanced). I would not judge the Nikon 200 f/2 on a d800 when you are thinking about getting the Canon 200 f/2 for a Canon body (possibly a 1Dx).
Normally, glass is a better investment than bodies and is kept longer. I would go with the 200 f/2 (which I own and use with a 1Dx).