So after about 8 hours of the progress bar being stuck at 30% I finally powered off the MBP. When powered back on it asked me for my password and then displayed some panic and debug info on the screen (in plain text) and then restarted and the process just repeated. Lucky for me I had created a bootable USB disk of High Sierra to install on my 2010 MBP so I booted off that, ran Disk Utility and First Aid which said my disk was OK, and then restarted the install from the USB. This time it upgraded without hiccups and only took about 40 minutes. Once it restarted I was up and running with High Sierra and my disk has been converted to APFS as well. Whew, didn't lose all my data and settings, although I do have a TimeMachine backup I didn't want to have to resort to that. So far all my apps seem to work ok with High Sierra although knowing Apple there will be bugs, their quality control these days would have Mr. Jobs spinning in his grave.