The DMV sys.dm_db_index_operational_stats includes columns for operations on indexes that result in write operations (such as leaf_insert_count, leaf_delete_count, leaf_update_count, and leaf_ghost_count). Since the operations occur for these at the row level, the counts tabulated on these columns can provide insight into the number of rows affected.
The DMV also includes range_scan_count which counts the number of operations on the index. This though does not include a count of the number of rows that were read in these operations.
The read count would be useful to use in comparison to write counts as a measure of determining if the IO on the index is practical for the index. For instance, if the database is writing to substantially more rows than are being read - the performance hit on the writes may be more important the benefit of the performance improvement for the reads.