Really? Millions of slaves? Cassanelli estimates total slave imports from Zanzibar at 25-50,000, beginning in 1800, peaking in 1846 and ending with the Italians. About a hundred years.
Your Maroon analogy can only refer to the Gosha and Mushunguli.
"Somali Bantu" is an unfortunate term created by the aid agencies that includes more than just Bantu ex-slaves. Notice that the population figure estimated in 1970 for the Gosha/Mushunguli was 80.000, and the current estimate, despite severe losses in the civil war and several hundred thousand still in Kenya, is thought to be over a million. This is not because of some miracle of reproduction. It is because the Gabawiin, Shabelli, Makaane, Shidle. etc, who arrived with the Bantu expansion ( the Madowweyn) and now, apparently the Eyle, have become added to the ex-slave Gosha and Mushunguli figures. It isn't real, but is being pushed by Samaale supremicists.
There are actually a lot of small studies on the Eyle, just no DNA data. By the mid-twentieth century virtually all hunters had turned to cultivation or moved to cities. There is a significant community of Eyle now in Mogadisho, working as butchers. There is damn little game left to be hunted.
This is from one of the country studies
http://countrystudies.us/somalia/40.htm.
"Most non-Somali peoples were primarily cultivators, but some, like the Eyle, also hunted, something the Somalis would not do. A few groups, including the Boni, remained primarily hunters into the twentieth century and were accordingly looked down on by the Somalis. By midcentury most of these peoples had turned to cultivation, and some had moved into the towns and become laborers."
When actual data becomes available, there will be little question about the answers. In the meantime. I think it is best to hold off making too many stringent claims.