The person working on that project does incredible work. I have one of his upgrades that added a 40 Mhz 68040, 128k cache, and Ethernet to my old SE/30, and it's been fantastic. I run System 7.1 on it to play around with HyperCard, Word 5, Excel 4, and a couple other old programs.
It's fun to make things in HyperCard as a great interactive and immediate feedback teaching tool for introducing my kids to programming. More than that though it's nice to sit down and draw inspiration from an era and implementation that went out of its way to take a handful of very well researched UI & UX metaphors and deploy them consistently and thoroughly. When I fire the thing up and poke around it feels like having the Software Engineer & Product Designer version of a serene Japanese garden. The transition from a little 9" B&W screen to my dual 27" LCD workstation is always jarring, and I always feel like the clarity of my thoughts and focus suffer immediately.