UKC

I'm looking for a new pair of approach shoes for hot weather. I get hot feet easily, wearing summer boots sucks even in 20 degree weather.  Trail running shoes are great for keeping my feet cool but I'm not sure how good they would be on more technical rock. 

Is there an approach shoe with a mesh upper? Or are shoes like the tx4 really breathable? 

TX Guide? It has a mesh upper and I've found them cool enough in hot weather.

(Caveat - read the review, funny shape to try before you buy)

Breathability is rather subjective but I really like my Scarpa Mescalito KN. No problems climbing up to UIAA IV rock routes in summer. They have also held up surprisingly well for a lightweight shoe. Crux Air looks to be even more breathable.

Another breathable shoe I have tried was LS TX2, but they gave me terrible blisters on the heel.

https://www.salewa.com/wildfire-mens-shoes-00-0000063485?c=516601

I've got a pair of the above, great in the summer, Breathable blah bla.

Have worn them as all day walking shoes as well as scrambling etc.

I love my Sportiva TX Guides but I do have narrow/low volume feet.

Scarpa Crux Lite? Not sure how readily available they are in the UK though - when I looked they seemed to be only available in the US.

Sportiva TX2s are the obvious ones, However I'm currently looking at Dynafit MTN trainers at the moment, sort of a cross breed between an approach shoe and a trail running shoe, they are light, burly have a mesh upper, and they look cool. however they are very hard to get a hold of since they are European, you will probably be the only person in the UK with those shoes if you get them.