Now you're making me want to try a 16 Homeworld 10/10/10/10 game on the X-map to see whether my PC manages to die before my units. I'm guessing that the first spirecraft wave probably ends up around 50k firepower or so.
I can see it now. Turtling up, thinking you are defended well enough for anything, and bam, 5 motherships and 5 Mk. V hunter killers kicking your door in.
EDIT: Oh, and welcome to the forums. 
Not actually new, just lost my old account. Thanks anyway though.
Those motherships are serious bastards, let me tell you.
I'm pretty sure no one will survive the first Exo wave on 10/10 at present with its x18 multiplier.
If so, mission accomplished! 
But honestly, some of the people who play this game: the cheese is strong with them. It would take a lot of savescum-experimentation, but they could beat that first x18 wave.
Exo waves tend to have a lot more bark than bite thanks to the fact that they stream in rather than appear at once. As long as you can keep up with the force of the stream the length of it isn't that important (does x18 spawn stronger groups or more groups? Will have to check). I don't think fighting off the x18 waves would be all that bad, the trick is doing it at 10/10 difficulty. Hence the need for X-map abuse, otherwise you can't simultaneously keep up a defensive line to protect against the normal stuff while having everything deployed to blunt a single strong force.
Fallen Spire ships should absolutely decimate them, which makes later waves survivable. Of course, that begs the question of just how bad FS at 18x will turn out to be. If the allies in the final stage don't scale up it might be an even fight there.
