Honestly, if you are going to go to the trouble of hacking then go ahead and go the Raspberry Pi route and put on it whatever floats your boat. Setting up one of those is pretty much the same difficulty of hacking one of these. I have one of these Minis and love it, but also have a Pi (well several actually) for things like Legendary Axe since there were licensing issues with the mini.
The only one I have hacked is the PS1 and that's because I got it cheap and the thing is pretty much garbage with the included game selection.
A hacked mini has value for me over RPI because it is WAY easier for kids or visitors to screw up settings on a RPI. On a mini, the worst they can do is overwrite a save state. The number of times I've had to reimage a card because someone botched something up is ridiculous.
Either way though, if you are willing to ditch a flashy front end, there are far better options than both of these.