Hi Arne,
as I've indicated previously, this really needs some thorough analysis and as I'm on holidays and in 'important bug fix only' mode, I really don't have the time for this analysis right now. Also, I think its a task that cannot be offloaded to somebody else as I simply have to feel comfortable with whatever we choose.
As long as our current work focuses on the actual GSM stack at the moment, there's no immediate need to find an answer either.
Regards, Harald