That would work. Before switching to scripting, you can also see if expressions can help you out.
The expression language in Grasshopper can deal with planes, points, integers, floating point numbers, strings, booleans (and, in the next version, complex numbers).
In order to get the z coordinate out of a point, feed that point into an F(x) components and use an expression like:
x.z
("x" is the default name of the variable, rename it to "p" or "pt" if you want it to be self-documenting)
--
David Rutten
david@mcneel.com
Robert McNeel & Associates