4.1 - I run MW first (no change to original account settings, no 127.0.0.1 changes, etc.), this deletes email from the server and hands off to OE. I then download remaining emails left on the server and avast scans them into OE inbox.
You can always swith off the automatic scanning in avast! 4.5 mail scanner and use it exactly as before (eg. vers 4.1) - as far as you believe, there are no viruses targeted for k9 and/or you're waiting for the first one to infect you. 
I am not using 4.5 beta, I tend not to use beta programs, especially for something as critical as anti-virus software.
I am not using K9 either - I use MailWasher which doesn't download the full email or attachments, only a small part (the size can be set by the user) of it to analyse/detect spam - It views that in plain text and doesn't execute code. When analysis and user input marks email as spam, etc. for deletion, they are deleted from the mail server. It is not a case of nothing is targeting MailWasher (not K9) and I am certainly not waiting for the first one to infect me.
I can't see how switching off automatic mail scanning is any sort of viable option to get arround double scanning, ditch email protection completely
Switching it off will not be the same as with 4.1 as currently I run MW independant of avast and have avast automatically scan my email. The option you suggest would remove email protection completely (unless I'm missing something here), not the same as 4.1.
I can't believe that you would offer that as a serious option, perhaps that's the reason for the
. So if it was not serious, why offer it?
