Looking for advice on next camera after a580

I'm currently using a Sony Alpha a580, but it's getting a bit tatty now, so I'm looking for a replacement.

My photography (hobbyist/academic) is mostly made up of insect (macro), wildlife, and live music (dark rock concerts to earn beer money), with the occasional portrait and light painting shots.

I have 6 lenses, and 3 flashes for the Sony, so ideally I'd stick with that system, but my immediate 'advancement' in terms of body would be the a77 and having (briefly) owned the a55, I'm very wary of low light shots using an SLT camera.

I see my options as either getting the a77 and potentially struggling at gigs, or switching system to Nikon or Canon. I've used a Nikon D90 and got on well with it, but didn't like the Canon 450D I tried.

Any thoughts and advice will be most gratefully received.