Hi All -
I think I got this sorted out after staring at the blog post referenced here and much trial/error.
I created calculated columns for the Monthly Depreciation and the life of the asset expressed in months. Then I changed my calculations for each of the years' depreciation amounts to be a SUMX of Monthly Depreciation * the correct number of months for that year (based on what month it was acquired) and left in the USERELATIONSHIP statement which is the key to getting the annual totals. I can now spread the depreciation over the years by referencing Year from the Date table.
Thanks for all the suggestions!