I agree with no DRM approach. All it causes is expense developing it (or licensing it from someone) and eventually it's broken (the fact that it exists will entice someone to break it).
About tracking who leaks packages, what will you do about it? Deny further access? How can you make sure this person won't find some other means of access? Take legal action?
To me it seems it's just too problematic trying to control software distribution.
Dunno if it would work better or worst, but what about not controlling distribution? Let anyone download the software and redistribute it
but make it clear that using it is illegal without paying the cost of the software (ie. with a notice on the splash screen or similar). Maybe allow for a trial period in this license.
Like this, the software is bound to spread wildly. Not everyone will pay for it though. Yet even the "pirates" will increase software's popularity and help spread the word. So even they contribute a bit.
On the other hand, some part of the users won't be very comfortable using the software illegally. This people would probably pay for the license to use the software. As long as a significant percentage does this, then profits can be made. The price would need to be set to the sweetspot that makes the most profits.
Another point to convincing users to go legal would be that they are supporting the developers doing so. They are in fact helping themselves by supporting the developers, as they will get more/better software as a result.
Now all this is very utopia-like, so feel free to disregard it.
Also probably not appropiate for a small market as the Pandora users. Just my ideas of what I would like to see. It's certainly much better than all the DRM crazyness happening these days.