That looks like a good tool to have. Maybe a little bulky for the tool pouch. The usual method of cutting drywall is to hold a non retractable razor knife and the end of the tape measure in one hand. First you measure, and make a small cut or mark, then reverse the tape and hold the tape measure in one hand and the knife and the end of the tape in the other. When you slide down the the edge of the sheet rock your finger takes a beating. This would help with that, and you don't have to mark once, switch the tape around, and then cut. However, you have to use the razor knife for so many more things, so this may or may not be a tool that he will use. Rockers are pretty tough cookies, your dad may be too set in his ways to bother with this tool.