I have always been sensitive to my wife's hormonal states, meaning I could feel the onset of her period and her ovulation. I could feel both about 48 hours before it happened. When she gave birth to our second daughter, I began lactating. I went to bed ( the evening my wife and new daughter came home) with man boobs and woke up with surprisingly nice breasts, that were leaking. A lot. Concerned that something was wrong, we called her gyno and he saw me right away. Strange moment when when Mr. A was called back for his exam! As far as the Dr. could tell, everything was as normal as it could be, for a lactating male. As a precaution, due to the pituitary producing the prolactin and an unexplained seizure in my past, he wanted an MRI done. All was well. The Dr said my milk was nutritious, the fat,sugar and protein contents were normal, I could breast feed.
My wife was against it. Totally. I think if I hadn't been TG, she would have been ok with it. I pumped milk a few times for a few days, hoping to keep things going, but she didn't give in and I dried up after a week or so. I really enjoyed the feeling using the pump, it is very relaxing. On several occasions, when the baby cried, I could feel the milk in my breasts being let down. The process was amazing. That my male body was able to change so I could feed my child was incredible. But I am sure the amazement would have been lost if I had to be the one feeding the baby whenever she was hungry - when it became a chore.
This is my only experience with a breast pump, and it was very pleasant!