My intact male (Stitch) used to live with his brother (Lilo) at another hosue. Both intact, same age, never been seperated. The previous owner was told they'd be fine staying intact because they were related.
They were fine for 2 years, then one night they had a fight. Nothing had been changed, nothing done differently, nothing to 'cause' the fight. Male dominence fights can get nasty, Stitch ripped off his brothers ear and damaged his tail.
The lady split them up imediately and then tried to re-introduce, they couldn't be put back together. She couldn't afford to neuter and buy new cagemates for both of them so she reluctantly had to sell.
Stitch came to me with a tuft of hair missing from his head, nothing compared to the state he'd left his brother in. Within 5 minutes of getting home he was eating out of my hand and to this date he is by far my most bonded glider. Personality doesn't really have anything to do with it, if anyone asked me about him I'd say he was the sweetest glider, I'd never have imagined what he could do to another male.
It doesn't always take a female, it doesn't always happen straight away and it isn't guaranteed to happen at all, but for what the outcome could be I don't think it's worth the risk.