Thanks for confirming that MultiFinder17. Please do some more testing with it to see just how compatible it is. In particular I think there are going to be issues with the Control Panel and sound. You also will have no way to adjust brightness, though the settings in PRAM should persist from the last time you set them. I would imagine since the early Systems patched the 64K ROM and 128K ROM, that there might be some changes to the 4th generation 512K ROM in the Classic which won't work as expected in System 1.0, so I wouldn't expect it to be especially stable.
Since you can't easily turn the Classic HD on and off, MultiFIner17, what was your experience (I'm assuming it was on)?
Having dealt with the HFS/MFS problem, I would suggest you will have no problems just booting up from an MFS only System disk (1.0, 1.1 & 2.0) with a hard drive turned on. The ROM will read the drive and load it on the desktop, regardless if the System or Finder know what to do with it. However, under NO circumstances try to write any data to the HD. If you merely read data off the HD, you should have no problems. Also keep in mind the Classic ROM is doing most of the work, but the System and Finder on very early systems have a limited capacity to recognize large volumes. Though I am not absolutely certain, there is no danger of an old System re-formatting your HD. At worst it should only ask you to initialize the disk as unreadable and of course you would cancel this request.
Since you can't easily turn the Classic HD on and off, MultiFIner17, what was your experience (I'm assuming it was on)?
System .97 IS System 1.0. AFAIK there was no actual System "1.0" released. System .85 is on the Guided Tour Disk.