It seems like cat ratings then are more suited towards actual electrical engineers in industry doing proper electrical stuff rather than aimed towards hobbyists who are only tinkering (unless they get adventurous and decide to rewire their home ?) So am I safe to assume for the sort of things I'll be doing (starting off with at least) the Anengs will be capable enough and if/when I want to move to more complex and higher voltage than what you'd find in synths then that is the time to move to a more expensive bit of gear ?
Essentially, yes. If you can stay away from the mains, the source of high energy, you should be good to go.
Stay away from large battery banks (arguably including automotive batteries) and large capacitors as well. The meters are fused on the current ranges and, more often than not, the fuse doesn't have a suitable rating. So things get exciting when you measure voltage with the probes set for current.
As with anything electrical, you need to take care. Check your meter setting before you jam your probes in a circuit.
Later on, you'll see why 10V stored in a 1 Farad Super Cap can release a LOT of energy if it gets shorted out.
I'm using the AN8008 interchangeably with my other meters. I work with low voltage stuff on my bench and I don't give it a moment's thought. For me, +-15V is about as high as I go. If I were working on tube amps, I wouldn't change a thing. The meters are fine!
I see no reason to work on line powered high energy SMPSs. If I need a power supply, I'll just buy one.