Becoming emperor and outliving the job are mostly dependent on the support of the army at that point, right? If so, it is not so surprising that the wages went way up…

Yeah that's what I figured. Julius Caesar marched on Rome with a hired army, then after his death Marc Antony and Octavian kept having to bribe their soldiers to fight and not switch side. Sounds like the army and leaders established an unhealthy precedent.

Mainly for the officers though. Of course kind of makes sense considering conscription became a lot more common in the later periods.