Fair enough @MarkA.Bachman - if your existing process ain’t broke, don’t fix it 
I believe my Grbl settings are the defaults produced by the Easel set-up process on a brand-new X-Carve, but the behaviour you describe definitely suggests your Z axis travel is reversed. VTransfer expects -ve Z movement to be downwards. The probing cycle triggers a -50mm move in Z (G38.2 Z-50 F100). If the probe is touched within that distance then it sets Z according the the Z Touch Plate Thickness setting under Settings->Configuration File Edit Settings… The default for the X-Carve is 15mm, which was simply measured from the probe kit I received from Inventables.
Thanks for the feedback though, I think I will add a start-up test to validate the Grbl settings are as needed in the next release. I have considered it a core principle with VTransfer that it neither changes any grbl setting ‘behind the scenes’ nor modifies the g-code that is passed to it - but since it does assume certain settings, it makes sense to warn if they do not match.
Cheers
E