i have never extracted from acacia, maybe someone else will chime in on that...
What I can say is that, first of all, NMT is also present in mimosa (see for example
burnt's tests), and in white spice pulled with naphtha and recrystallized, or similar only has 2% impurities, basically NMT. If you check our
WIKI, you see NMT's xlogp being lower than dmt, and just a bit higher than dmt n-oxide. Considering n-oxide isnt very soluble in aliphatic naphtha/heptane/hexane, it is a sign that NMT is probably also not too soluble in these solvents. Though this is not fool-proof way to tell, sometimes there are exceptions, only testing with pure NMT would tell.
Shulgin says it doesnt seem very active but then again from what he says its neither conclusive. Also one thing is activity by itself, another thing is using it together with another alkaloid, pharmacology can change.
If you do extract from acacia confusa, let us know the results!