The Arcean's have really gotten the short end of the stick in the new upgrade for their technology trees. Basically, their ability to use mining bases and starbases is greatly limited, similarly the ability to develop an economy is buried deep in the tree. So, it seems to me that the Arcean's are too 'proud' to worry about money. In compensation, their factories, etc, are cheaper but their production rates don't seem to be much greater.
The upshot is that in small maps, they do okay. They get rapid speed bonuses and have the first shot ability. As the maps get larger, the opponents quickly begin to out-tech them (especially the Drengin) and then the Arcean's are dead meat.
I really like the feel of the Arcean, it fits well with the backstory on them. However, I'm not sure I could ever win with them on a map larger than medium. I might be able to make better planets but with no effective starbases or mining bases, in the long run they will lose.
I have no good suggestion on how to 'fix' this, if indeed it should be fixed. Perhaps others have ideas?