Switch from mostly Canon to Sony, maybe?

Not quite sure why the thought of switching has hit me lately. Maybe because it's that time of year where my photography slows down and it would be a good time to experiment with a different system.

Anyway I'm thinking about selling the 1ds miii and maybe the 24-105 and picking up the Sony a7/Zeiss 55 f/1.8 and one of the cheaper 85s to play with for awhile. I'll be keeping the 135l and my canon 50 f/1.4 for the time being at least.

Since I shoot portraits/seniors/enga​gements/weddings I think the Sony a7 and some fast glass should be able to handle it but would like some thoughts from some early adopters on what they think.

I would do it if it were me. You still have the 5d.

The A7 has some advantages for portraits with face detection AF (no more focus recompose, now you can compose and focus!). You won't lose anything in the ISO department but you will gain a lot in the weight loss and size department and in the tech (for example, panorama shots).
Samyang are modifying lenses to fit the A7, just extending the mount length, but with focus peaking you are looking at having a lot of fast primes for 1/3 the cost of their counterpart lenses. Just an option.

I would go for it!

Thanks for the response. I really would like to try a lighter ff body and that 55mm zeiss is a lens I think I will love. So far the images I've seen taken with it wide open are nothing short of eye opening.

If the sony is 1/2 as good for portraits as I think it will be I'm going to be very happy.