Should I use a comma or em dash before "including"?

Question

Which of the following two versions is preferable, and why:

1. This document applies to all systems, people, and processes that constitute the organization’s information systems, including board members, directors, employees, suppliers, and other relevant parties.
2. This document applies to all systems, people, and processes that constitute the organization’s information systems — including board members, directors, employees, suppliers, and other relevant parties.

The only difference between the two is whether a comma or an em dash was used to set off the final part of the sentence ("including board members..."). The purpose of this question is to better understand the difference between the em dash and the comma.

The following issues are not relevant to this question:

• Whether people can properly be considered as part of an IT system.
• Whether there should be spacing around the em dash.

Answer 1

It’s a matter of taste and context.

I personally generally use em dashes in pairs for asides, or to clarify a sentence with many commas. In this case there are many commas but I find the em-dash jars rather and would not use it.

As in many case where there is a problem with clarity, I would split one sentence into two.

This document applies to all systems, people and processes that constitute the organization’s information systems.

This includes board members, directors, employees, suppliers and other relevant parties.

Answer 2

An em dash is used to provide an aside.

Imagine you are speaking to an audience. You come across a word or idea you aren't sure they understand, e.g.:

The organisation's information systems.

Naturally, you pause mid-sentence to explain/define that idea. This is where your em dash comes in.

Is the comma separated sentence okay?

Sure. But it isn't as clear, nor as literate, as the alternative you offered.