The bitcrusher example shows the onboard compressor running, it's OK, but limiting as a post processor on the "What-u-hear" output. I found it tricky to adjust to get a pleasing sound.
I think the audio library will way outlast the SGTL5000 so it would be a good idea to implement a software one.best instrumental ringtones
Compression is usually applied heavily on drums and guitar but less so on vocals / samples etc, truth is you need a setting for every track if you really want a good mix.
Whats good for drums, might ruin vocals for example.
Of course it depends on your project as to whether this matters at all.