When I configured mine a couple of weeks back (latest firmware) I tried using the safari plugin, and part of the installation required me to put the browser into 32bit mode. While annoying it might bode well for older pre Snow Leopard macs but I don't know about PowerPC (I just got rid of mine).
I did have problems with the initial configuration (admin password problems - seemingly a bug) but once the first configuration was done the plugin tools worked fine from a mac.
I don't remember seeing a way to explicitly manage the bit rate, that seems automatic, but you can select high or low quality options from the iPhone/iPad clients, which presumably has the same effect.
I've been flipping back and forth between the plugin config tools and the "old" mac desktop tools without issues, largely because thats the only way to install bin files for non standard IR devices at the moment (browser plugin tools are in beta, but PC only at the moment).
Hope that helps, I'm pretty new to this thing too.