Impressive. I keep using bare xterm since it still supports Tektronix emulation (but, unfortunately, no Regis nor Sixel). This seems like a viable substitution for all three.
xterm actually does support ReGIS and Sixel graphics! However, it must be compiled with --enable-regis-graphics` (or `--enable-sixel-graphics`); and it's likely that your distro didn't compile it with those flags. If they did, you can get ReGIS support by running xterm in VT340 mode (`-ti vt340`).