I've met a few of them.
Incredibly nice people they were too.
Like hell would I pick a fight with one, even if he's asleep
One of my shift partners was a Gurkha, the other a Para so we had each others backs, great times. As you say incredibly nice people but don't ever let them drive a car, seriously, worse drivers ever! We had a taxi driver bring a sleeping Gurkha to us, the driver had tried shouting when they'd got to the barracks but he hadn't woken up. The driver said he hadn't wanted to shake him as he would have anyone else.
On the other subject, my father had been an army boxer, when he'd came out he'd got a civvie job but helped coach at one of London's boxing gyms, Freddie Mills was someone he helped coach and spar with ( Freddie is long before anyone here's time I think). My father used to bring me with him sometimes when my mother wasn't well, I learnt to box at an early age and he kept teaching me as I got older. When I got into martial arts umpteen years (decades) ago I had a good bit of sparring experience albeit just the punching, but the footwork was good.

In the RAF I got to spar with not just martial artists but also boxers, most of us were shift workers so in most sports it's hard to practice with the whole team or other practitioners of what you do so you make do. A karateka/kickboxer was better than nothing to spar with and vice versa. Twenty years ago I got involved in MMA so got to know more boxers who came to our club for the sparring, we help with regimental boxing teams as well which we all find great fun. And yes we try to persuade them to turn to the dark side MMA.
I have also seen an inordinate amount of fights between civvies and military, military and military, even civvies against civvies, military wives against other military wives, the latter is more scary than any other type of fight, trust me.
A couple of friends of mine run bare knuckle boxing fight nights, yes it's legal here, just not sanctioned by the boxing authorities. Kick boxers have a go on them, some do well some don't and guess what, some boxers do well some don't. Who'd have thunk it eh!!!!!