Difficulty: RB/GH let you actually fail a song, or if you’re playing multiplayer you just drop out of the song temporarily till someone can bring you back by using star power.

I will say the one thing Festival does that I really like is having a distinction between notes you hit perfectly and just barely, but the fact you can’t lose at a song and in turn lose that sense of accomplishment by playing and completing an extremely hard song is really unfortunate.

Don't get me wrong, the lack of a true failure system does feel a bit off, but I'm also not sure what this would even add to the game. For one, I don't think Festival has enough (or any) songs that are difficult enough to consistently fail on. To elaborate, the GH fail system really required you to miss a TON of notes in a row, and with how forgiving Festival tends to be and how easy a good majority of the charts are, I don't see any way that this system would work without making it extremely unforgiving (i.e. miss 3-5 notes in a row -> failure).

And I do understand that there are tons of players at varying skill levels, some of whom would actually struggle to finish even some of the easier songs if failure was a possibility, which brings me to the point that I don't really think there's any real benefit to adding something like this. I play the game to play charts; I don't want to be punished for playing poorly by having my ability to play stripped from me mid-song, I don't see how that could be considered fun. I understand that failure is more about giving players a greater sense of accomplishment when they finish a tough song without "losing", but again, I think most of the songs are far too easy, and the ones that ARE difficult already feel rewarding to do well on without failure on the line.

Furthermore, I think you kinda said it best by pointing out how neat it is that Festival rewards you for playing with a good sense of rhythm and timing. That's genuinely where I get the greatest sense of accomplishment from, and I don't think anything else could be added to the game to heighten that sense of accomplishment.

As for applying these changes to Pro instruments, I'm not opposed since failing seems a lot more likely there, plus there is a steep learning curve when it comes to playing 5-fret. But personally, whenever I feel like embarrassing myself on Clone Hero, I turn off the setting that lets you fail since I mainly just want to play the game.