I greatly prefer XM over Music Choice in terms of programming, variety, and sound quality.
The occasional announcement or promo doesn't bother me at all. In some cases, as in the intelligent commentary offered on XM Classics by Martin Booksmith (a musical scholar, formerly of NPR), the commentary adds to the experience.
But, then, I critically listen to music and prefer good radio to mediocre aural wallpaper.
As per the unhappy 18 month old, was that Radio Disney or XM Kids? Radio Disney is what it is (it was also on Music Choice). XM Kids plays a lot more music. There was no other kids choice on Music Choice than Radio Disney (since For Kids Only was taken off years ago), and so the 18 month old has only gained by the change.