Great post as always Rick, but I'd caution that PROC COMPARE is quirky about missing data and the SHORT option could result in an oversight.

Here's the PROC COMPARE SHORT output when comparing sashelp.cars to a copy data set with the 'Length' variable removed (code below):
NOTE: No unequal values were found. All values compared are exactly equal.

The note at bottom of PROC COMPARE output could more accurately be read as "all values that were able to be compared were found to be equal," which is not the same as "these data sets are identical." This variable mismatch only appears in the "Variable Summary" section of PROC COMPARE output, which reads (in part) "Number of Variables in SASHELP.CARS but not in WORK.NOLENGTH: 1."

Sample code is below:
data noLength;
set sashelp.cars;
drop length;
run;

title 'PROC COMPARE SHORT with missing variable';
proc compare base=sashelp.cars compare=noLength SHORT;
run;

title 'PROC COMPARE with missing variable';
proc compare base=sashelp.cars compare=noLength;
run;
title;