As an academic exercise, a while ago, I tested an application that displayed 15,000 records in a ListField, in a 7290 (very old device). Once the data was loaded, display and scrolling etc was pretty quick. So I would say you should have no problems with the number of rows you have.
Like all these things, there are different ways of coding this sort of application. In addition to what has already been suggested, I think you should think about your application design and the way the User Interface works, to make sure you are processing the data in a way that provides the best User experience without exceeding the capabilities of the BlackBerry.
Typically someone else's design will not work for you, so I suspect rather than attempting to copy what BBDeveloper has done, you should think about how you want your application used and design around that.
Amongst things that I would recommend that you avoid are:
a) Adding individual Fields to a Screen for every item in your list
b) Processing your List (for example sorting it) on the Event Thread
c) Creating a useable version of your List from some other format (e.g. XML) each time you start the application
Hope this helps
