One year ago, I had the same doubts, then i searched a lot and a lot. guess what??
aeron is the "mother" of almost all booms, a lot of sails brands and accessories don't have and dont need to have their own molds to produce their booms, harness lines, extensors and other things. what they do? They ask to "secound ones", it's normal! The only change the grip.
the booms like aeron, old simmer, RRD, gunsails, goya, unifiber (not all), duotone EPX, prolimit, they all are made on aeron and others that i dont know.
i think but i'm not sure, new simmer, loftsails, avanti, they are made in another factory, but i dont know.
of course i bought the gunsails carbon boom, i have the 180-240 and the 230-290 what can i say?? I do like, but i only tried alumunion booms. this gunsails booms are the only 100% carbon booms that i have, i cannt compare with others.