Frances:
I am running Mac OSX10.6.8 with a WIBU key and can open AC back to version 7 under Rosetta, later operating systems will restrict you to AC10, and Mavericks to AC12. I am currently in the process of upgrading to Mavericks, but will keep a separate hard drive or partition to be able to boot into OSX10.6.8 when needed. There are also
File Converters on the Graphisoft web site to help with this.
A few terms I don't know from your post:
ArchiCAD16Solo: Is this the full program, or a restricted version?
v8.6: There were 8.0 and 8.1, I don't know what 8.6 is
With the full version you should have no issues running different versions of AC simultaneously (I don't know about the Start editions). As to taking a file from AC16 to AC17: it takes an effort due to the addition of the new attribute
Building Material, you can read the help guide and threads on this forum to see if it is worth the effort in your case.
You should add a Signature to your Profile (click the Profile button near the top of this page) with your ArchiCAD version and operating system (see mine for an example) for more accurate help in this forum.
David