Thank you for a detailed and thorough reply..you made your case
and I learned something new. One thing though is not true (as stated in the article you linked under PS), a BlackBerry CAN work without BIS/BES. It requires a bit of simple hacking but is doable (Shangmail/Funambol for push mail, Opera mini for browsing, Google Mobile App for mail/news/navigation, Nimbuzz for IM).