I'm in both fellowships, too. Both fellowships are very careful about even mentioning the other by name during the meeting. I go to AA as a supplemental thing, but I hear good messages from the people there. I work an NA program, however. The felowships are divided for a reason. There is enough in the traditions that say they do not support each other. This is where the whole of the Sixth Tradition comes in. These traditions are set in place to avoid controversy and problems of the primary purpose of each group. If we don't follow these traditions then a break down in the system (I hate that term) results and the individual groups tend to fall apart.
I tend both NA and AA speaker meetings, too. Many of the ones working the AA program tel their story which includes drugs more times than not. It's jut rare to have a single addiction these days. The stone-cold alkies are still out there, but nowadays it's joined by dope more and more.
I like following the Traditions. It keeps a sense of stability and focus for a disfunctional set of people where opinion get get us into trouble. If we stick to the foundation there's no room for the "self" to f*ck it up.