That is an exceedingly scarce variation, congrats on acquiring it.
I've been keeping my sights set on one if 1) I could find one, and 2) if it had the round trigger guard.... unfortunately I've been skunked on both counts, and I fear if one ever show'd up it would have the square guard like yours.
As to the original owners ascertion that this was an answer to Glock, I'd not necessarily agree since the "Mini Gun" concept had been around with S&W for years, the original guns were the M469/669 guns, followed by the Third Gen versions, and then during the "gun of the month" timeframe all the assorted variations surfaced.... TDA/DAO/Decocker versions. Of the DAO guns, the scarcest ones are the blue variations, the M6944 is the one I've been looking for to finish out my fledgling DAO collection, but I've focused on the later round trigger guard versions.

Oh well.....

Neat gun!

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.............SmithNut