August is a long ways off, are we likely to see any sort of performance increases or optimizations beyond the expected 5.4th on the SP30?
No. They are quoting estimates straight from simulations that may or may not be correct. Remember, they are jumping node processes so it is a complete craps shoot.
Is that just a low ball estimate of power and it'll end up being faster, or is that a best case scenario?
They are quoting best case power estimates and guess what, if they don't come in on spec, the power supplies chosen won't be able to handle extra capacity so they'll have to completely redesign the PCB and the box will end up running slowing at the same wattage.
Are you able to ship sooner than August if everything goes well?
No. They are quoting August as a "flip a dime three times and it lands on it EDGE everytime" timeline. I've asked them to post their timeline and contingency plan in this thread and they have decided its not worth it to be "transparent".
Any sort of other perk to this process that makes investing the money to buy something so late worthwhile at this point?
No. You are taking on their risks for the $$$/BTC spent.