I am exploring ways to recreate our fairly complex symbology library from ArcMap in ArcGIS Pro (2.2).
Currently, we symbolize by unique values on an attribute; symbols are the same but in different colors (e.g. Active is green, Abandoned is gray, Proposed is blue). Attribute-driven symbology seems like a reasonable candidate for these layers. While I can find some resources about how to enable and use attribute-drive symbology, I'm having a much harder time finding actual use-case examples to read about.
What are advantages of using attribute-driven symbology over the familiar unique value symbolization? Conversely, is there anything that we might lose by transitioning? (For example, using Arcade expressions will reduce the numbers of analysts/developers who have the skills to maintain and update symbols.) I'd appreciate a discussion of the pros and cons to help us make a more informed decision.
I would like to share a couple of thoughts on this, hopefully they are helpful in determining the best way to go forward.
Arcade is a language which is pretty powerful and allows us to do a lot of things in a more simple way, for instance calculating the time elapsed from a date stored in a feature, without having to implement trigger at database level. Although you can do a lot of fancy complex things with Arcade, most usages are very simple and don't require special knowledge. I would encourage that you start to explore the possibilities, since Arcade is becoming more and more important throughout the platform.
For the example that you described, I don't see the necessity to use attribute-driven symbology. You can still use the unique values and assign a symbol to each unique value. In case you have many values and already have a field with the color name and fields with RGB intensities, the attribute-driven symbology can be a very powerful way to define symbols based on these values. In that case it will be more effective to use this feature.
So what I am saying is that it's very good to know that these possibilities exist and how to use them, but it is also important to know when to use them and that is when it will provide you a more effective way to define the symbology or provide some additional functionality that you cannot obtain using the conventional ways.
If you're using the unique value renderer in ArcMap and it works for you, you should probably just use the same in Pro. Note that the standard renderers are recognized as a typical way to reflect different aspects of the data in the Attribute-driven symbology help: Attribute-driven symbology—ArcGIS Pro | ArcGIS Desktop
Don't overlook that note in the documentation about performance: