AppleScript Numbers: missing value test fails?

For completeness sake, here's the alternate code that works:

Note that the same test is performed - but in this case it works without any problems - making the fact that it doesn't work in the 'if' part of the code all the more confusing.

Am I just not seeing something that would account for the difference?

Actually, I just figured out a difference - line 74 checks for missing value on the 'keyValue' string, and since that works (apparently) it doesn't actually hit line 77 to check for a missing value on the 'rDate' string.

If I create a data line that has the appropriate keyValue but no date string - it fails exactly like the 'if' clause -- so the issue seems to be with the test for missing value on a date string (even though it is being explicitly set to be a string).

BINGO! - That was the problem, it was coming back at the literal string "missing value" and not the figurative value. Putting quotes around the string in the test case(s) solved the problem.

FWIW, given my current data set, the timings for the two alternatives was:

-- Do date comparison then key match test (IF)
0:00:26.32
AppleScript 0:00:03.32 12.6%
Events 0:00:23.00 4916

-- Do key match test then date comparison (ELSE)
0:00:15.17
AppleScript 0:00:00.00
Events 0:00:17.54 4601

So, for now I'll do the key match first.

I now need to re-do my Automator script as a [just plain] Script, to see the performance of doing the insertion of the formula and then copying it over to verify that handling it all internally (above) is better in the long-run.

Thanks again SG - you are the King!

FWIW - the formula method appears to be decidedly faster - it just seems slow because you see it set the formula in each cell as it is processed - but the exercise was still a good learning experience (for me).