Modding disc-based console to let you play games stored on solid state memory:

Pros:
- Much faster loading times.
- Can carry your entire library with you.
- Built-in backup of your game library in case of disc rot or something.
- Overall much better experience

Cons:
- There's a certain... feeling to knowing that the console is actually physically reading a disc to let you play. Like you're playing the game the way it was "meant" to be played. e.g., on the psp, I still think UMD is really cool despite the fact that severely hampered the experience of the PSP compared to the cartridge-based DS. It's kind cool hearing the UMD drive spin & move the laser while playing. However, I do not play UMD games on it. Instead, I dump the disc to the sd card and then play from there.