We have been a hybrid office for years. Unfortunately, it's often a problem. Here are some of the issues:
1. Senior management sees ArchiCAD as a 3D rendering tool, and AutoCAD as a "primary work machine". It may be backward, but this is difficult to overcome when they don't have any interest in the technological explanations. Executive buy-in is critical.
2. You will always have employees who resist, usually because they are "done learning for this lifetime". Ironically, they often hate AutoCAD so much that they just stick with it, because they think the next software may be even harder to learn.
3. When you finally do get ArchiCAD into the project stream, the first-project learning curve often costs hours. When a budget overrun occurs, it's the first thing to get blamed. Project Managers are then afraid to give it a second chance.
4. Using both programs creates a burden on the CAD Manager. Though some standards translate fine, many do not, so you are forced to create 2 sets of standards, 2 templates, 2 training tracks, all the time checking for incompatibilities. In my case, I'm also a (the) Project Architect, so most of my standards remain half-finished.
5. Hiring existing ArchiCAD users, especially junior drafters or interns, is nearly impossible. Most applicant know AutoCAD to some degree.
6. In a small firm like ours, many of the projects are quick-turnaround remodels. We get the DWG as-builts from the Owner, verify and correct them, add a couple of walls, and ship them out. Sometimes, it just makes sense to stay in AutoCAD, so you can make a profit. The people who specialize in those projects don't even understand why you're trying.
7. The Autodesk marketing juggernaut will often undercut you. About once a year, you'll have to do damage control when a Principal comes to you and says "we should switch to Revit (or ADT/AC Architecture)... this ad says it's an easy transition!"
I would encourage you to bring in ArchiCAD where you see a need. Try it out, use it for special projects, and try to get the most influential people in the firm to like it. If it takes, then push for complete domination. If it doesn't, don't beat yourself up. Some firms are made to stay in the last decade.
Just one man's opinion.
Chuck Kottka
Orcutt Winslow
Phoenix, Arizona, USA
ArchiCAD 25 (since 4.5)
Macbook Pro 15" Touchbar OSX 10.15 Core i7 2.9GHz/16GB RAM/Radeon Pro560 4GB