The simple answer is that yes the procedure is similar with scp and tftp.
I think that in answering this question more fully, it is helpful to separate discussion of which protocol is used to transport data from the discussion of what data is being transported. The most commonly used protocol is tftp. Cisco also supports scp, rcp, and ftp to transfer data including configuration files. The choice of which protocol to use is separate from consideration of what data is being transferred. If you would like to use scp then I see no reason why you should not use it.
When you copy to running-config you can copy only parts of the config or copy the entire config. The choice of whether to copy all or part would depend on what you are trying to do. In either case whatever you copy is merged into the existing running config. In copying config data the running-config is NEVER erased or deleted. In fact the IOS does not have any way to erase or delete the running-config.
On the other hand if you copy anything into startup-config the existing startup-config is always erased and completely replaced - even if you only copy part of the config file.
The different behavior of whether the existing config file is erased or not is built into the copy procedure on the router and is not affected at all by which protocol you use to perform the data transfer.
HTH
Rick
HTH
Rick
