Blur is just Motorola's bloatware "overlay" on top of vanilla (bone stock) Android. Some functions and apps/additions to Android. Non-blur roms dont loose any functionality, but some is just replaced with stock android.
HDMI out is a blur (Motorola) app, hence the reason it will not work on blurless, same with the radio app. A few apps have been ported over already.
IMHO, blurless is the way to go....the phone runs MUCH better and you dont "loose" anything. But thats just my personal opinion.