Brian,
There are important differences between the two CNC. If you’d like a quick overview of the differences then look at the Windows Desktop of the Shark PC. We’ve placed a list there as a reminder for people who go through the certification class with @csader.
Describing the certification as “training” would be a bit strong. It’s more like an orientation that ends with demo cut. The point is not to teach you CNC; knowing CNC is a prerequisite. The Shark uses Vcarve software but a different CAM software. The Shark doesn’t have end stops so planning boundaries is an issue. Hold down is a T-track clamping system, dust collection is a shop vac, etc. We just want you and the CNC to stay safe so we stress what’s different.
The Shark HD3 is a lovely little option which is rarely used.
Get certified and rarely ever find it not available!