Aside from its outward appearance (silver instead of dark blue or whatever) :>) the Pronto TSU 2000 has more user-available memory than the TS 1000, although I have never heard of anyone actually running out of memory with the earlier one.
Of even greater significance for those who like the idea of a "point and shoot" remote, rather than one which REQUIRES a lot of programming is the TSU 2000's built-in database of remote command codes for a vast array of brands and components. While it is as programmable and customizable as its less expensive predecessor, you don't have to do any of that to be "up and running". With just a few easy menu choices, tryout of the selected template and installing it (via another menu choice) or moving on to another trial template, you can replace the other remotes for your system fairly quickly. And this is all self contained within the remote itself, not requiring a computer hookup to upload codes and templates (although again, that is still a feature that you can use if desired).
I had lost the remote for one component and recently purchased another where the remote was "optional at extra cost". The Pronto TSU 2000 had code templates that worked well for both units without ANY further customization.
The TSU 2000 also has a rearranged user menu for somewhat more "intuitive" navigation. And it now allows you to customize some settings, such as turning off the infernal "beep" that accompanies every "button" push otherwise.
I like having a remote that can (at my discretion) take advantage of all the power of programming of the earlier model but is easy to use virtually "out of the box" without it. For me, that was well worth the extra money. This isn't because I am averse to programming, per se. It is just that I do a lot of it at work, and so it simply doesn't have the hobby allure for me that it does for many other folks. (I wanted a remote I could use, not a second programming career.) :>)
Good luck and enjoy!
Burke