When in 16 Mutes mode there seems to be a slight inconsistency in behavior. I think it may be in relation to orienting most of the sound control parameters to control the entire beat, but a couple things struck me as odd.
On the Pads screen, you are still able to select a sound (holding shift and hitting a pad) but it is not reflected graphically on the display (this could be fixed if the display matched the style of the Mixer screen as I posted earlier). Also, It seems like it may still be of value on this screen to be able to use the "Mute", "Solo", and "Delay On" buttons, but they are inactive.
On the Mixer screen, things get a little thicker. You are able to select a sound (holding shift and hitting a pad) and it shows you that selected pad on the display, which is nice, but those same three "Mute", "Solo", and "Delay On" buttons are inactive, yet there is the ability to toggle the Mute and Solo features using the soft control knobs. Stranger yet, if you hit the "Delay On" button, it does not toggle the Delay feature of that sound, but it brings up the Delay related screen which gives you the ability to toggle the Delay feature using the soft control knob. It really seems to me that those 3 buttons which are just waiting to be used should be active on this screen. Further, when you imagine this scenario on this screen, it makes more sense to make it consistent and have it available on the "Pads" screen as well.