Hi LordLiverpool,
I have a very similar issue as yours (and GoDaddy's customer service has been less than UNusefull).
I still don't know where the heck the redirect comes from. I didn't even have the dudamobile code in my .htaccess file! (only the DNS records pointing to it, which I changed in order for the mobile subdomain to point at @ - just like you did).
I had been getting the pageok blank page until I found this:
http://blog.arunkumar.biz/enabling-wordpress-multisites-sub-domains-godaddy/
Now my mobile subdomain shows the content on the general domain, because it is pointed there. But the redirection is still occuring and, since I have no idea what is provoking that redirection, I ca't stop it from happening.
I just wanted to share that turnaround with you so at least your mobile visitors will see something and not the dreaded pageok page.
I hope we find what the culprit is so we can finally get rid of that unwanted mobile redirection...