Sorry not sure what you mean by all the POP checkers …
If you mean all of the YahooPops, FreePops, MrPostman …yes they all work the same way using localhost ports (but they all have different default port numbers).
The important issue is making sure that avast! can get in to check the appropriate local ports.
This is one of the reasons I am an avast! supporter. The avast! team have made it remarkably easy to specify in the redirect tab interface differing ports that need to be checked for all those different POP3 converter programs … (just as long as you remember to uncheck that “ignore local communication” box.
Other antivirus products have yet to catch up to avast! in this respect.