I have found that you can touch up or even repair minor edge issues with Spyderco's medium ceramic hone, so aluminum oxide will work...though diamond will make the process a whole bunch easier imho, especially if it's more than a mere touch-up. I have no personal experience with CBN.
I've used a 1200 / 2000 combo Venev bonded diamond hone (1x6" version) to maintain a Maxamet Para 3's edge and it worked fine as well. I've not (yet) used any plated diamond on my Maxamet knives.
Congress Moldmasters (SiC) would be another good option if you wanted to look for an inexpensive alternative.
ETA: It appears Sharp Guy and I are on the same page.