CARP improvements

Hi guys,
  I would like some input on how to best tweak CARP with a very small change:
as it is now the canonical URL is used to define the hash for next parent.
It is very efficient - even too much.

I'd like to add a variant to it so that only the host part of the URL
is used as initial key for the hashing.
This will decrease the effectiveness of the balancing, but make it
easier to cope with some websites which do not like it when requests
travel across different routes.

There are three ways I can think of to address this:
- change the way CARP works - it's an one-liner
- new global setting
- new carp option (e.g. hcarp or host-carp)

What do you think is the best way to implement this?

Thanks

-- 
    /kinkie