it is more work initially because you have to fill in a lengthy application form - well, in surrey you do at any rate.
advantages that i can see are: 1. being quality assured 2. having regular contact with you coordinator to talk matters through and to go through some standards every now and then 3. free training on various topics 4. many free resources 5. you can draw down nursery funding once you are accredited and you cannot be accredited unless you are part of the network 6. it was useful to say that i was on the network when i applied to do the eyps 7. shows a certain type of commitment to your work (and i don't mean this to read that non-network CMs are not committed!!) 8. play and learn sessions arranged by the coordinators 9. many outings arranged throughout the year that are funded.
disadvantages: 1. you must be committed and go to a certain number of training sessions and / or play and learn sessions. 2. can be cliquey to some extent