THe ASACP is, in effect, a tool for the adult industry monitoring itself - and nothing wrong with that. If it closed down a few pedo orientated sites, so much the better.
As far as being the most effective route, probably not. In the US there are specialist regional units of the FBI and prob relevant that alleged offenses are reported direct to them. They have all the tools available (tho they may not say so) to act rapidly.
CP is not just about porn images - the background, and more serious issue, is about child abuse. Since the net is global, it is also relevant that alleged offenses are reported quickly and direct to specialist law enforcement units where these offenses take place.
Another organization which has direct reporting of offenses in most countries is the IWF. This is a org sponsored mainly by leading net names, Microsoft, News International, Google, Nokia, Lycos. Adobe, Verizon etc and the EU.
IWF is in effect, acting as a clearing house and reported offenses are transferred to law enforcement units in whatever respective countries where complaints can be investigated. These may not only be a matter of CP, but have other underlying serious crime attached, with possible obvious child abuse involved.
Depending on the country where the offense is likely to be rooted, it's prob better to report this directly. Time can be meaningful in starting the ball rolling. IWF has "hotlines" to agencies in the follow countries: Australia, Austria, Belgium, Canada, Cyprus, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Lithuania, Netherlands, Poland, South Korea, Spain, Taiwan, USA - tho will deal with any CP content anywhere in the world by liasing with Interpol and other serious crime agencies. Currently the IWF handles around 27,000 "incidents" annually plus several 1000 other computer/net related offenses from fraud to serious crime.
The URL for IWF is:
http://www.iwf.org.uk
Here's their lastest report in a condensed/simplified version:
http://www.egovmonitor.com/node/8246