Typically, a digital mixer will give you way more processing power than analog. In order to use this processing power effectively, you have to understand how it works and how to access and adjust the various functions. Using a control surface tends to be fairly intuitive, as long as you understand what buttons to push and how it effects the layout of the control surface. Each control may have multiple functions.
You typically get a bunch of faders. Each fader controls a different channel. But you can have layers as well. Say the board has 16 channels but is set up for two fader levels to cover 32 channels. Fader level A will be channels 1-16 and fader level B will be channels 17-32. In this case each fader controls two channels, but only one at a time. So you have to be aware which fader level you are actually on.
You may also be able to use the faders for different functions. For example, the boards I used could be setup to put the aux sends on faders or assign the sliders of a graphic EQ to the faders.
The aux send levels could also be accessed second way. They appeared in a sub menu of the selected channel with rotary controls. Most of time I preferred using the aux send on fader menu to set levels, but sometimes the selected channel sub menu was a better choice.
AFAIK most digital mixers use a selected channel format for most of the controls you find on the channel strips. So if you want to adjust the EQ on channel 13, you select main fader level A, and the select channel 13 before adjusted adjusting the controls on the selected channel portion of the control surface.
There is also likely to be range of different virtual menus you need to understand to either configure the board or to access advance features.
The process for accessing and adjusting tends to be a bit different on a tablet, and some features and functions may not even be available on the tablet surface. Sometimes you have the option of configuring what functions are available via tablet, and you also may be able to configure which menus are on top. Since you are planning to use the tablet for mixing, you will want access to the main faders, selected channel section, aux sends, etc.
If you were planning on mixing on a physical control surface, you might configure the tablet to show some of the more commonly accessed sub menus. The idea is you are extending the functionality with value-added apps, rather than using the tablet as a primary mixing surface.
In your case, you could consider setting up the tablet as your primary control surface during sound check. Then during the show, you could mix on the physical control surface and set the tablet up to expand your view, so you don't have to step through sub menus to get to a critical function that my require quick access.
I resisted going digital for quite a while. When I finally started working with a digital board, I found it to be way more efficient. I also found that my mixes sounded significantly better.
To me the biggest disadvantage with digital is maintaining familiarity with the interface so that you can quickly and reliably step through the menus and make the exact adjustment you intend to make. I mixed on Yamaha digital mixers. A problem I had is doing to exact key combination to go from the main mix to the aux on fader screen. I found that frequently I was selecting the matrix on fader screen. So I sometimes wound up making the desired adjustments in the wrong place.
If I have not mixed for awhile, I like to pull the board out and hook up some speakers to practice going through the necessary menus and sub menus. If available, it's a good idea to have access to the manual. I personally prefer searching for solutions with soft copy on a computer, but if it is available, I prefer to read from the hard copy manual (way less confusing and easier on the eyes IMHO).
Gool Luck!
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