Hi there!
Here's my experience regarding the $19.99 BIS. I called in last monday to order my new Bold 9700 and was also told that the $24.99 BIS is REQUIRED. Of course I was bummed about it and keep pleading my case in keeping my old $19.99 BIS to no avail. In the end I have no choice but just to agree on the $24.99 BIS. After I hang up the phone I tried using the chat service online, hoping that one of the Tmo agent can help me change it back to $19.99 BIS. I even use the Blackberry forum as an example saying that other DO get to keep their $19.99 BIS (hehehe), but still that agent won't let me keep mine.
Today though I called in again to talk about other issues regarding my text messages and at the end of my conversation with one of the Tmo rep, I once again brought up the topic of keeping my $19.00 BIS for my new Bold. This time the rep I spoke with was more nice, friendly and accommodating. She understood my concerns about paying an extra $5 bucks for the new BIS. She put me on hold for a few minutes and then came back to me with a good news about being able to keep my old $19.99 BIS! Of course I was sooo happy after hearing it . The only condition she told me is that I can no longer remove the $19.99 BIS in the future if I decide not to use Blackberry anymore -- which was fine with me.
So you see based on my experience it really depends on the Tmo rep you spoke with. If you can't get it the first time, try calling back some other time because you might get lucky the next time you do .
Good luck all!