About cost balance of Elite/Marines, here is a first point:
The 4 IPCs and 7 IPCs Marines unit transportation cost is relatively balance on the long run, when a player can use for a second time some transports.
After the first travel, where it is better for Marines unit, the transportation ratio is reversing toward regular units.
FIRST TRAVEL / SECOND TRAVEL, same transport
Cost ratio for Regular unit transportation:
3 (transport + Inf + Inf) 3 (Inf + Inf)
3 (7+3+3) = 39 IPCs /6 grounds = 6.5 IPCs/unit / 3(3+3)= 18 IPCs +39 = 57 IPCs/12= 4.75 IPCs/unit
2 (transport + Inf + Tnk) + 1 (transport + Inf + Inf) (4 Inf + 2 Tnk)
2*(7+3+6) + 1*(7+3+3)= 45 /6 units = 7.5 IPCs/unit / 12 + 12 = 24 IPCs + 45 = 69 IPCs /12 = 5.75 IPCs/unit
Cost ratio for Marines unit transportation:
2 (transport + Inf + Inf + Inf) 2 (Inf + Inf + Inf)
2*(7+4+4+4)= 38 /6 units = 6.33 IPCs/unit / 2*(4+4+4)= 24 IPCs + 38 = 62 IPCs /12 = 5.167 IPCs/unit
2 (transport + Inf + Inf+ Tnk) 2 (Inf + Inf + Tnk)
2*(7+4+4+7)= 44 / 6 units = 7.33 IPcs/unit / 2*(4+4+7)= 30 IPCs + 44 = 74 IPCs /12 = 6.167 IPCs/unit
So, after a second travel, with the same 12 units the transportation ratio is improving for regular units compared to Marines ones:
for 12 Infs vs 12 Marines Infs = 4.75 vs 5.167 IPCs/unit.
for 8 Infs+ 4 Tnks vs 8 Marines Infs + 4 Marines Tnks = 5.75 vs 6.167 IPCs/unit.