Hello,
No, Adaxes 2016 doesn't yet support PowerShell 4. We are planning PowerShell 3 for the beginning of 2017, PowerShell 4 is yet to be considered.
As a workaround, for now, you can start your PowerShell scripts in a new PowerShell instance. Since it is going to be a separate instance unrelated to Adaxes Service, the limitation of using only PowerShell 2 will not apply there. The latest version of PowerShell installed will be used. For information on how to use the workaround, see the following script sample: Run script in new PowerShell instance.
Would love to use something like gShell instead of GAM to interface with G Suite.
Actually, we've even tried using gShell our scripts, but eventually discarded it. The thing is that currently, to use Google APIs, you need to get a unique authentication code each time you start a new PowerShell session and connect to your Google organization. A quote from gShell documentation:
After you hit enter after typing that in with your own username and domain, you will have to interact with a scope (permissions) wizard in PowerShell - just follow the directions. Once you have finished your primary browser will open up taking you to a page asking you to authenticate.
For this purpose, gShell is completely unusable with Adaxes or any other automation system. This is why, when making scripts for customers, we opted for GAM.