Well, a nice surprise, my DNS-345 was waiting for me when I got home this evening. I had picked up a APC UPS on the way home, and loe and behold, after all the setup was done it is recognized. So I'll add this unit to the 'compatible' list, as ShareCenter System Management reports it:
UPS Status
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Device Information: Standalone Mode.
Manufacturer    APC
Product            Back-UPS ES 550G FW:843.K4 .D USB FW:K4 
Battery Charge 100 %
Status              On Line