I'd second Dave's suggestion that we leave the POISSON list as is. Aside
from the overhead of multiple lists, confusion might reign about which
list is discussing which topic, with people ending up posting to multiple
lists, etc.
The increased focus may also help with the problem that POISSON has had
with meeting at IETFs: when it is scheduled opposite other meetings, there
will always be participants who have no possibility of attending; in
particular, most of the IESG will be busy in other meetings.
More focused WGs will not need so much attention.
True, fewer people would attend the more focused groups, but wouldn't
they still face scheduling conflicts with other WGs?
(Feel free to tell me if I've missed the point ...)