Must you upgrade to 4g for the iphone 5s?

I have an iPhone 4S and I was wondering if I truely wanted to get the 5S, would I need to upgrade to 4G network? I'm grandfathered for unlimited data, that is my reason. Want a new phone, but not paying data rates. Usual downloads is 7gb/months. So yes it is a huge cost increase.

No I don't need the ' ifail ' BS either.

Its the same, 4g is just faster and drains battery faster.
Also if your worried about data use the Wi-Fi so it won't use your data plan up.