I wouldn't say that the Black Madeira or the I258 I tried have complex flavors. If anything rather simple. You can break down their flavor in two parts:
1. An immediate berry flavor
2. Followed by a rush of very sweet honey
That's what sets Black Madeira and similar tasting figs apart.. they have BOTH a berry and honey flavor. Where as the large majority of figs only have one or the other. However... neither the berry or honey flavors taste complex to me-- the honey flavor tastes like honey straight from the store drizzled on top. It's better than any honey fig I've tasted, but the berry portion doesn't rank very high. I've tasted quite a few berry figs now with a much more complex berry flavor to them. Azores Dark, VdB types, Negretta.. all have much more interesting, complex & rich berry flavors to them that are very difficult to explain.