It's only science
Implementation
The design, construction, and use of the XY2 is 'open'. As such any limitations of the system are considered 'self-evident'. The principle limitation of the design are:
Stepper motor drive: Fundamentally these (as are most) stepper motors are driven without encoder feedback. Therefore it is possible for the motor to 'stall' and thereby lose steps, thence the position will be lost rendering the CNC control invalid. The XY2 has been engineered to provide generous torque to allow deep groving and practical milling, but ultimately the depth of cut, feed rate and cutting tool are determined by the user.
Belt transmission: Belt transmission allows practical drive over long distances economically compared to a helix (acme) screw and nut (re-circulating ball nut). However there is a more tangible back-lash with this arrangement (approximately 0.3mm). However the direct drive of the system (no gearing), plus the backlash compensation settings that are settable in MACH3, means that the resultant CNC CAM workpiece can be finished to an extremely high quality.
Use as XY (NC) Drill
There are not any perceived limitations of the drill function within the specifications stated.
Use as Router
As the XY2 is controlled by the MACH3 software, there is virtually no limit to the capabilities of the X-Y table. Obviously there are practicalities such as removal of dust/ swarf as well restraining the item which is worked upon. In additional, because the system is controlled by stepper motors there is always the possibility that the system may lose steps due to excessive torque requirements. It is up to the user (i.e. you) to ensure appropriate feeds and speeds (depth of cut) to prevent missing steps.