Syntax for "quantity/unit"

Sometimes, units are best expressed as a denominator below the corresponding quantity/description as in section 9.3 of the documentation:

In graphs and tables, repetition of the units following each entry or axis mark is confusing and repetitive. [...] Much better is to show division of all quantities by the unit, which leaves the entries as unitless ratios.

Also from SI brochure:

For example, the equation T = 293 K may equally be written T/K = 293. It is often convenient to write the quotient of a quantity and a unit in this way for the heading of a column in a table, so that the entries in the table are all simply numbers. [...] The axes of a graph may also be labelled in this way, so that the tick marks are labelled only with numbers, as in the graph below.

I'd be happy if there is a macro for this purpose. Let me call it \varSI (maybe there should be a better name though) and interface I'm thinking is like

\documentclass{article}
\usepackage{siunitx}
\begin{document}
\begin{tabular}{rr}
  Syntax & What it looks like \\
  \hrule
  \varSI{time}{\second} & time/si{\second} \\
  \varSI{mass}[e3]{\kilo\gram} & mass/SI{e3}{\kilo\gram} \\
  $\varSI{c}{\meter\per\second}$ & $c/\si{\meter\per\second}$ (or $c/(\si{\meter\per\second})$?)
\end{tabular}
\end{document}

In the last example, I'm not sure if the unit with multiple components should be grouped by an explicit parens. I couldn't find authoritative references regarding this point.

Not only \varSI looks more semantic to me at least, but I also believe that introducing this kind of stuff will encourage the users to more respect SI-compliant notation.