I'm in the same boat. The company I work for just switched to a BYOD policy. Eventhough I already had (and still have) an HTC EVO, I decided to purchase a Blackberry for my work phone.
Just like you, I use my Blackberry for work activities...corporate e-mail, corporate e-mail, etc. And it works great for my purposes.
I have, however, been told by the IT Department that the company will be decommissioning (shutting down) the BES server in November or December. So it looks like I will have to give up my Blackberry.
So as the song goes....Another one bites the dust....