Nashvegas, I would not put one day olds in with one week olds, since the tiny ones are just too fragile and wobbly. Your temp requirements are slightly different too. I do not think the week-olds would intentionally harm the younger ones, though. A lot depends on your brooder set up and space. It's pretty easy to make a brooder from stuff most animal people already have around. I could probably set up 5-6 right now just from stuff I have in the garage. Hmmmmmm. . . . . chick hatching . . .
Anyhow, I am sure there are others here with different experiences and opinions. That's just my own preference from the five years of chick hatching I have done.
The biggest issue I have faced with my birds surrounds the "coop drama" from housing different breeds together. I have raised many different breeds of large fowl and bantams, and now that I have thinned down the flocks to one breed per pen (plus silkies), things are so much more calm and enjoyable - - no feather picking, no pecking and chasing, no fights, no feeder bullying, minimal nest box drama. Just something to think about as you are exploring different breeds.
Good luck!