"Scientific" socialism versus what you label as "idealistic" socialism is the equivalent of Protestantism versus Catholicism: two iterations of a religion (it is not that commonplace yet to see Marxism and the Hegelian dialectics from which it originated as non-theistic religions but replace 'god' with 'man-as-god' and you'll understand the comparison). Both Catholics as well as Protestants consider their religion the true one while the others may have heard the bell but are lost when it comes to locating the clapper. The same goes for all your various strains of Marxism, good for endless philosophising by academics as well as for being regurgitated by Lenin's [1] 'useful idiots'. How many angels can stand on the point of a pin? Does historical materialism show the inevitability of the end of Capitalism? Philosophise away but don't forget that's all it is: philosophising without basis in actual reality.

[1] whether Lenin ever used the phrase I'll leave in the middle but the concept stands