I wear both, plus I also have some mesh armoured pants for summer touring as well. TBH anything that's going to give you protection is going to be hot when you're wandering about off the bike. Let's face it when it's 90 degrees even jeans and boots and going to be warm...
I have two pairs of Kevlar jeans. One pair by Red Route that have kevlar like this
And another pair by Hood jeans in the UK that are almost fully lined with kevlar,
Red route are lighter for summer but being a baggy fit I'm not confident that the panels would offer much protection. Nothing scientific just the feeling I get. I have total confidence in the Hood jeans but they get pretty toasty! Another plus for the hood jeans is that they have a long velcro strip sown into the lining which allows you to fit the armour exactly where you want it (Knee and hip) The red route has pockets and, for me, the armour doesn't sit right on the knee - but there's no way of altering it.
Leathers I wear these, Richa street:
I love them, comfortable fit, padded knees with armour pockets. Have a fairly classic look about them too. No knee pucks coz I ride like a grandma!
Yeah they're hot when you get off the bike but if I'm out riding it's not much of an issue as I don't spend much time off the bike!
Hope there's some info there that helps.