Well I do ban by rcon. But since I have several servers I prefer how HLSW handles SteamID bans wherein you can just add a ban by HLSW's own ban list and then transfer it to another server without a hitch.
It's just that when HLSW handles IP's it mistakes them for SteamID's...so when you go to your other server and choose 'Add all bans from database', you'll have Steam_3
:512 or something like that on your ban list.