I guess its that we have an iPod or iPhone, and probably sync these pretty regularly. We have them on our person so dont need to remember to take them back in the house/office and we dont need to keep music in multiple formats.
For me the iPhone + Adapter gives me Music, and Sat Nav all in one solution. Worth the 75 pound! well £65 from Chris@Souls!
Yup, i use my iPhone for Sat Nav & Music, iPod is great, what i do alot tho is download an album to home, put it in my library then stream the album over the air from my home server to my iPhone via ORB, works a treat well worth the cash tbh.