I had good training with the ZHxM device yesterday, with the proper voice alert.... However I did lost capability to hear music. Only one track was played and after that the music was stoped. After I finished my training and disconnect ZHxM the music start play again. It looks for me that there was conflict between blue tooth devices. I used blue tooth Headphones Sony with Media Player.
Yes it does have that function. You can define upper/lower limits for the heart rate in Main Menu > Training Settings > Interval Training. If you define just one interval, the limits are always active.