The precise export bus appears to have a limit of 8 buckets per operation. Some things (such as GTCEu) have operations that need more than 8 buckets at once, and I was hoping to simplify my setup there. Is it possible to up the limit? Or have an upgrade that does so?

I've noticed this issue myself while attempting to set up automation for processing raw fluids with Modern Industrialization, as there are a number of different recipes, but only a set amount of space within the chemical reactor's interface.

I had a look at the sourecode, and I think we're hitting a limit of 64 operations, as AE2 has the fluid transfer rate set to 0.125 buckets per operation, and 64 * 0.125b = 8b:
https://github.com/AppliedEnergistics/Applied-Energistics-2/blob/8910159484a5d0d51e8eb372a3837abe78bad733/src/main/java/appeng/api/stacks/AEFluidKeys.java#L50-L54

The fact that we can set up to 64 buckets at a time in the GUI is likely just an oversight on the ExtendedAE developer's part:

To get around this in my own automation, I ended up hooking up a pattern provider to the chemical reactor, and exported the results via a crafting card, as the pattern provider seems to be able to place more than 8 buckets without any problem. Otherwise, the ME precise export bus seems to be the best choice for exporting fluids in bundles that are equal to or less than 8b at a time.