I am probably not a typical Balance 20 buyer but I bought a Balance 20 for my home simply to get myself more downstream bandwidth and to ensure reliability (DSL 5mb/512k and Wireless point to point 6mb/3mb)
I worked great but my Bittorrent client (used legally!) and my PS3 both hate the Balance. The PS3 lists the NAT as STRICT and enabling or disabling UPNP and NAT-PMP doesn’t change anything, it still lists it as Strict, though I seem to have fewer speed issues when I have both turned off.
The bit torrent client won’t connect at all. (MacOS 10.7, Transmission as BT client) whereas it worked fine before (iMac to Airport dual band, to Balance 20)