This means that you can specify all kinds of stuff like owner,group and mode of added files - so that removes that as a problem.

The only issue I see it is the .arf file extracted to a ram disk, and if so, then later files in .arf file will simply overwrite earlier ones right?
then thats a no-brainer too - simply update or append your new kernel to the .arf file via cygwin tar and let it rip - yes the arf files grows, but who cares, for now its a simple fix.

We already know that this all works, I included details of how to do it on my web page. You don't in fact need to end up with a substantially bigger ARF file because you can also delete the old zImage file from the ARF file.

However, all of this pre supposes that the Receiver user is willing to download and use the cygwin software. Some of them will do that, some of them will not want to.

My tool (which should hopefully be finished later today) is for those who are unwilling to download and use the cygwin tools.