I've been a practicing infantilist for more than 30 years. My current nanny loves to breastfeed me, and I've had four other babysitters who have as well. All but one offered to breastfeed me; I did not request it.
For me as a big baby, suckling is a strangely calming experience. The women who have breastfed me have been aroused, amused, or bored with the experience. In many ways, being breastfed is even more intimate than having your diaper changed or being bathed, since it involves 'mommy' sharing a part of herself with a big baby. If you have a strong maternal instinct, you may find it a very fulfilling experience. If you enjoy the dominant role, or if AB play is more arousal-oriented for you, you may enjoy it even more.
The real problem is positioning. Even lying side by side, it's hard for the AB to be comfortable breastfeeding ... especially when the mommy has large breasts. My nanny likes to cuddle me while I nurse, which is enjoyable but can also be uncomfortable. Some of the AB breastfeeding photos show the AB almost sitting up in the mommy's lap. That's a nice image and it's a wonderful experience, but it's not something I can do for more than a few minutes at a time. Over the years, I've found it easiest if my mommy or nanny sits on the bed or floor and holds me against her breast with her left arm. The bulk of my weight is on the floor or bed as well, rather than on mommy's lap. In about half the interludes I've experienced, mommy's other hand went to my diaper, which can be quite nice.
I'd highly recommend a nursing bra or a nursing nightgown, depending on your situation. If you're going to nurse often, the nursing bra is a big help ... especially useful if you intend to induce lactation. If you're wanting to nurse your SO or boyfriend, the nursing nightgown facilitates that sort of intimacy.
In contrast to Orionstar's experiences, I enjoy nursing as I'm being put to bed. Particularly with the lights off and my nanny's hand fussing with my hair or caressing my face, nursing at bedtime is an extremely relaxing experience.
I hope you have some mommy-types or babysitters adding their thoughts. I know you're more interested in female feedback; as Orionstar and I have noted, nursing is a very warm and loving experience.