Does donor insemination really work better than husband sperm if older mom?

No: Successful insemination depends upon both male and female factors. Primary male factors, with insemination are :- 1)sperm densiity (number of sperm/ml) 2) %motility & 3) % of normal or abnormal forms. Thus use husbands semen if his parameters are normal, more so because he will then be the biological father.

Donor better: This is not always true, many other factors.