the problem about class evolving is the +3 in their respective unit cost

so assuming you would start the game with 10 unit point with 1unit points / sec:

you can deploy the in 8 seconds (their unit cost is 8 and 10 respectively)
in an evolved class, it would take 6 sec more..... (14 sec)

but if you can cost reduce them.... you can deploy them as fast as possible and use skills a possible. however, they are fragile to enemies.......

so its hard to defend against rushes or im just a stupid person on this forum.....