Traffic upgrade 5.2.1 to 5.3

[Florian Hengstberger]

Hi!

I want to upgrade my box from 5.2.1 to 5.3 stable.
I have limited download, so, if I update the sources using cvsup
in order to make buildworld ..., is there a way to roughly estimated 
the traffic.
Case it's impossible, what's the typical order? A few MB, a few dozen
MB or more?
Another thing is that there seem to be problems with the avr-tools
my current work depends on. Is it somehow possible to keep this package
as it is while upgrading. 
What about upgrading the kernel only?

Thanks a lot,
Florian