20 MB blocks means you need 41 Mbps upload. Most people don't have that even available.
Please share your calculations.
20 MB = 160 Mbit.
8 peers minimum.
30 seconds maximum to upload new blocks in a timely manner.
160 Mbit * 8 peers / 30 seconds = 42.67 Mbps.
Only if you are miner you need that speed. For normal user you can do that in 5 minutes and you are still more then fine. EDIT: "Also who say you will send out to 8 nodes? If you are slower you might send that to only one." Miners are connected directly and have bater connection and don't relay on other nodes. And I have second cheapest option at home and it is 10/100 with no limits(none has limits just to be sure). Is internet really that bad in US that this can be an argument that 40 Mbps is so hard to get? But anyway 4Mbps is more then enough at 20 MB