I have a label system something like this in Gmail:

+COMPANY 1
+COMPANY 2
receipts
payments
legal

Basically the + are companies and the non+ labels are labels I use across all companies so I don't have to create tons of duplicate sub-labels inside each company.

Issue is that Airmail labels things (ie the color triangle) in the inbox by first alphabetical label but it puts +XXX at the end of the list whereas Gmail puts it at the beginning.

Small thing but makes a big difference when trying to see what's what at a glance.