Well this seems to be more than just an exercise in getting the settings to stick for 2 different APNs.

I have finally managed to get internet2.voicestream.com as APN for Cellular Data and wap.voicestream.com as APN for MMS to stick.

However I still can not send MMS msgs. A speed test confirms i'm connected via Edge and not GPRS.

Maybe wap.voicestream & internet2.voicestream cant play together?

Maybe i should try a different APN...