Finally found some time to invest into the stripped-down qemu approach.
Now I have a 200K (probably can be made smaller but for a test this
should suffice) binary running on my SLES machine basically doing
what qole achieved with the 3 vde daemons.
I observed a thruput-issue as well: Limitation to 570KBytes/s per
TCP-stream. As pcap doesn't have any knowledge of TCP-streams
and I don't think it is a delay/windowsize issue it probably
originates somewhere inside slirp. Though with a 100KBytes/s
shaping per TCP-stream of many servers and the bandwidth offered
by the providers I have been using till now this is kind of academic.
CPU-Load isn't dramatic as well.
Now the bad news: Last time I used scratchbox was chinook ;-)