I agree their bites can be quite hard. Normally they can be quite large so you can hear them.I didn't know it was only the females that bit. I wouldn't say I've sensitive skin, it's just I'm always getting bitten by them so I'm always on the look out for them. Seem to be everywhere at the moment.
I got bitten by a cleg when I was 15, and ended up with lockjawThey're a bit like a guided missile, once they've locked on to you as a potential target they won't usually leave you alone until they've landed and had their fill. Not much fun if you're prone to allergic reactions to insect bites either, so get some good insect repellent and bite ointment if you're out in cleg country at this time of year!