the insignia NS-DV8G and the x20 are very similar. i've read that the x20 is a rebranded insignia or vice versa. anyway, the most important part is that they have the same brains (telechips tcc8200) and mp3 decoder (texas instruments TI TLV320AIC23B). the bad part is that there is no sound with the insignia firmware. more details
here. check the rockbox forums as i'll post there if i succeed in anything. I've seen some new features on insignia, such as audiobooks (i guess it may have text support, but didn't test it) and some useful settings such as turning off the lcd completely while listening to music. now, i reflashed my x20 back to iriver 1.07