Can installations of X1/X2 and 8.5.3 exist on the same disk drive or machine without adversely affecting one another?  I'm OK with working on an 8.5.3 file in 8.5.3 and an X2 file in X2, but do the executables share any common configuration files, etc. if installed in different directories such that one might interfere with the other?
 
Can I install X2 without installing X1 a/b/c first?
 
Thanks!

I have 8.5.3 32 and 64 bit producer along with X1 Expanded x64 and X2 x64 all on the same computer. All work fine.

One thing you'll have trouble with is opening a project in 8.5 or X1 which has been edited in X2.

But that should be pretty obvious to anyone moving onto a new version of an existing piece of software.