Hi,
As far as i know wccp is more flexible in the relation with the cache (you are testing the service directly with the cache, and you are talking with caches), with route-maps you can´t do this you only can test the interface you are sending the traffic.
WCCP consumes more cpu in the router (It uses GRE to send and receive the traffic to cache servers). We are using L2 wccp to reduce WCCP consumes CPU, I´m afraid you can´t do this with the 2600.
I hope this helps.