Unless you have multiple devices connecting via b/g & n, I would say save your money. The new one is great, it's what I have. It's nice not having the AEBS throttling down while I'm surfing the net or gaming the moment a b/g device connects.
The guest network is a great feature, there are numerous uses for it. If you have roommates you can have them use the guest feature while keeping your personal machine safe from them. Not saying they would do something intentional - more along the lines of "hey what happens if..."
My roommates share the guest network and they have no clue. My guest network is the only one that broadcasts the SSID as well. There are other reasons you may want to have this feature, that's only one example.
Ultimately decide what you NEED, then decide if the higher price for the "other" things will be worth it in the end.