The difference for audio is extreme, definitely worth the purchase. I own the 2910, definitely a great player, haven't had a chance to audition the new HK31, but I'm sure it will deliver for the price. May not be at the same level as the 2910 though.
I bought some cheap cables with the player to keep the dent in the wallet down, will upgrade later. I bought WireWorld cables, all 6 for $50 - no complaints.