... the setup is ready now and waiting for the "split" to happen... as I said, it might take minutes or days...

That sounds like a typical IBSS split problem. You can analyze it by
using tools like horst[1] or ibss-merge[2] on an additional machine
running in monitor mode.

Also, iwconfig might show different Cell IDs in its output.

"might" ???

Also, one of the things I've tried is to manually set the cell ID using "iwconfig wlan0 ap <whatever>", and does not seem to work. I'm now using "iwconfig ap" BEFORE the interface is up, to see if it helps at all.

BTW, I've regularly seen the "ramping ping" problem, should I try your patches?. Which ones?, what'ts "madwifi_ibss_merge.diff"?

Best regads.