I don't know how many of you have 6000 credits lying around in order to purchase one large ship. By the time I have that many credits I'm building huge hull ships in one to three turns. Conclusion: like most costs in this game mercenary ships are out of scale and will rarely be used because it's not economical.
I'm sure playing as the Arceans and Torians will be fun for the lore buffs out there and for those looking for a change. If this campaign is anything like the original release one, it will not be worth playing, even for story reasons. Hopefully they were able to really devote time to a rich and immersive campaign experience this time.
For me personally, what will make this expansion awesome is if they make the game more manageable for larger maps, like with the previously proposed constructor/starbase changes, shipyard sorts, filters, and bulk-obsolete, bulk upgrade and decomission, and bulk planet focus-changing. So I will wait until after the expansion release to see if they have accomplished these before I decide whether to purchase.
P.S. Is there no simple ruler capability to measure the distance between two hexes? I'm tired of counting hexes all the time.