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.