Mark, I don't understand why you are recommending the 72xx and 75xx series Blackberry for deaf people. The screens on those devices are smaller than the 77xx series; granted, the form factor for the former is smaller than for the latter but it would stand to reason that deaf/HOH people would find the bigger screen more useful due to the fact that they would not use the blackberry as a phone. Please comment.
The 77XX series:
(1) Do not have much memory for 3rd party software. Such as chat software.
(2) Cannot hold the thousands of emails that the deaf wants to hold
(3) Performs noticeably more slowly (even the 7780 too!)
(4) Are less stylish and more bulky
(5) Are less user friendly, they don't have a TCP/IP stack out of box, you hafta do the pain of installing OS4 on them before chat software works properly.
(6) The 7750, for example, is 5 times slower than the model 7250.
(7) The keyboard is more important. The 7290, 7520 and 7250 keyboards are the best BlackBerry keyboards.
This is why I do not generally recommend the 77XX despite the bigger screen. There are good reasons for the bigger screen, but unless you need thick glasses, the smaller screen is perfectly fine. The other advantages and chat-software user-friendliness of the newer models vastly outweigh everything else.
In the order of ease-of-use, here goes:
7290 on T-Mobile (easiest, since chat software is preinstalled)
7250 on Verizon (network software runs out-of-the-box)
7520 on Nextel (sometimes flaky at first)
7290 on Rogers
7290 on Cingular (a little harder, requires frustrating chats with Cingular CSR's)
Due to TCP/IP blocking issues preventing chat software, do not get a 7250 on Bell Mobility. Also Sprint/Telus is unknown at this time, so I don't trust them just yet -- until I hear that VeriChat and other software "runs out of the box" on them.
HOWEVER... the 7730/7780 models are relatively good if you can work around limitations. Just bear them in mind. You don't need to sell your 7730 if you got everything working, saved a little money, and you were smart enough to do all the upgrades yourself. Then your 77XX can do almost everything the newer models can. Just be lucky you didn't get a 775