hmm i see!
well the lenses i have are
- 70-200 f/4 IS L
- 100mm f/2.8 macro L
Also an ef-s 10-22 and a samyang 8mm fisheye for my 600D which i'll use for a second camera which performs quite well in 1600-3200 iso and these lenses doesn't need fast speeds. f/5.6 and 1/60 are ok even for a large print 30x40cm
i'll buy an ef 50mm f/1.4 along the the FF camera. (i love the creamy 1.2 but it goes way beyond my tight budget
The way i'm thinking of it.
my FF will play with the 50 1.4 and the 24-105 for start
and the 600D with 10-22, fisheye, and the 100L which is ideal for head portraits as it becomes like 160mm
Your 10-22 won't work on a FF body (you may know that already though). I'm not sure if the 8mm is FF capable, but that would be almost tooo wide for wedding work
Also, I was on a 7d before upgrading to the mk3 (I also had the 10-22). I tried my best to use both side by side at weddings. But, I found that the 7d became a very heavy lens holder...It did great at outdoor ceremonies, but the difference in IQ above ISO 1600, that is a game changer and yeah, led to my 7d just sitting in the bag all day, then not even in the bag at all, then sold to a friend who was going to africa and wanted more than a P&S. So, be ready for your 600D to become a dust collector!
Also, after you snag your mk3, you could sell the 600d with 10-22 and then the 8 mm and snag yourself a 6d as backup body.
Lastly, I see your hot to trot for the 50 1.4, but, take a good look at the 85mm 1.8...same price basically but IMO a much more useful lens!
either way, be ready for the 600d to become a paper weight!