> Will I be able to use 1.7 with everything else Groovy related if I install
> the libraries independently?
As long as you are not trying to link against both versions, you should
be fine, I guess.
> What is different about ros-groovy-pcl and a vanilla version of PCL?
You need to use pcl_conversions, as in Hydro.
Specifically, you will need to check out the Hydro pcl_conversions source to overlay ahead of the Groovy pcl_conversions, which will not work with PCL 1.7. Be careful not to put any other Groovy code using PCL in that overlay, unless it has also been converted to use the new message interface.