The only roo I see is the Light Brahma.
Leghorns do have bigger combs than other breeds at that age and can look gangly.
If your Dark Brahma is a bantam it will be ok because they are being raised all together.
Mine is from Ideal also and it is smaller than all my other standard size chicks. If fact I have a couple larger bantams that are the same age and just slightly smaller than the Welsummer. In my experience, and I have...
It does look splash but when I checked the Splash OEGB chicks on Ideals site it looks nothing like them.
Most of what I got in my assortment were OEGB. It is getting more "splashing" as the feathers are coming in.