When using Radius server, the downside I can foresee immediately is device compatibility, which for a home user will be a deal breaker!
For offices it's immediately apparent why you need 802.1x authentication
1) Most importantly prevents users on the same access point from listening to each other. Because there is no common key, a user will not be able to decrypt over the air WiFi signals from other users.
2) Flexibility to change access credentials as you please. This is critical in an office for example, if an employee quits the company, simply remove his login or if you suspect his login has been compromised. Does not affect everyone else.
In terms of security, the extra keying helps to improve an already very secure WPA2 AES encryption so I can't say it will help your home out if you are already using a very complex passphrase.
What do you guys think?