LightMP3 allows you to underclock to 20 while setting the bus down to 95. Though it is better in that it is more specialized, this is easier to use since you just launch your music normally and then use as you would.
It really is just your choice, whether you prefer to get better battery life and features at the cost of having to wait just to launch your music or use something that integrates with the PSP so seamlessly that it feels like a Sony added feature.
Maxime, the TC already said they are working on it but as long as you can still use the sleep mode in games and the homebrew that supports it I see no reason why it would really matter. Though I don't really notice how often I use sleep mode in the XMB until it is gone.
Chibisukee, seems your release is fairly popular. Just look at how many jumps it has gotten on the front page.