There are gates on every channel. There is not the option to switch them to downward expanders. This is a VERY desirable feature and has been requested many times.
Personally, I gate the kick drum and perhaps one or two other percussive sources. Gates on other channels are nearly useless as hard gating is audible due to their strict ON/OFF nature. Expanders are gentler, less obvious and can be used effectively on sources containing more than merely a heavy transient tone without bringing excessive amounts of other stage sound in and out of the mix.
The option to choose gate/expander can raise the bar on your mixes. If Presonus can do it, I’m sure A&H is capable.