Wil Intune suffice for our Mac fleet?

The answer is that it depends on how good of a MacAdmin you are. I'm being serious here. InTune *can* provide a basic structure for managing Macs. It is a fully-qualified MDM and it can give you a base layer, but that's about it. You're missing quite a lot like package building and management, pre-built configuration profile templates, and more.

If you're a seasoned Mac Admin with good scripting knowledge, you can engineer solutions that can make InTune get to the same or similar functionality as Jamf (or another mature MDM).

For a small fleet of Macs like yours, you might actually be better off with an MDM like Mosyle or Kandji -- both of which have done a lot to help newbie Mac Admins get their fleets managed with built-in tools and add-ons that provide a lot of value and automation right from the start.

Yes, of course it'd be nice to just use InTune/MEM as it's often built-into the cost of a Microsoft license. And InTune is getting better, but in my opinion it's not there yet. It is not a mature macOS management tool. (even while we manged ~15,000 iPhones with it).

If you only need to cover the security needs you mentioned (since your users are admin), it sounds like you'll primarily use your selected MDM for Configuration Profiles.  Intune's Configuration Profiles was not as pretty to configure (last time I used it), but in use is works 1:1 with Jamf.

When you start discussing things like package deployment (outside of Mac Apps) and Standard User management, Jamf start to become a clear winner.

If you are already used to Jamf, Intune will feel like a severe downgrade, like losing an arm level stuff. 

If you haven't used device management before, Intune will suffice.