IF you use the digital audio connections on the receiver AND the program is transmitting in Dolby 5.1, then yes, you will get additional audio channels.
There are 'some' Dolby channels, but the vast majority are musicam audio.
ALL the HD channels, by there design spec. carry Dolby 5.1.
Any programs encoding in Dolby Surround, like the Simpsons can be handled with analog L+R via the musicam outputs.
Good audio always enhances the viewing experience.
Go for it.