UKH

For years I have been using Merrell moabs as my approach shoes... work shoes... in fact all-round living-in shoes. They're great except I find them very hot and sweaty if the weather is the slightest bit warm. In fact I'm convinced they have made them hotter and sweatier in the last few years (I have an old ratty pair to compare against). I am certain I haven't accidentally bought the goretex-lined version.

So, sadly, my question is can anybody recommend an alternative that is a comfortable all-day shoe that breathes better than these?

Just bought some Adidas terrex tracerocker for 34.99 due to my meindls giving me athletes foot in this heat. So far so good. Comfy, light, breathable and decent grip. 

Inov8 Roclites are great for this.  Also some of Salomon X Ultra models.  Both are open mesh, no membrane.  Like you, I find a lot of shoes hot and sweaty.  I have both the Inov8s and the Salomons.  I prefer the Inov8s because they're ridiculously light and very grippy on rock and turf.

Salomon Speedcross 4 for me. Utterly awesome. Light, comfy and all 'round good. Wore them for travel to, 3 days hiking and scrambling in chamonix and swimming in french lakes over the weekend just gone, running today and smart enough almost for semi smart casual if purchased in black.

As a slightly different option, you could consider Evolv Cruzers. They're very unstructured and the upper is almost all canvas so they're immensely breathable. Not a like for like replacement to a standard approach/trail shoe but I really rate them. They're also delightfully cheap.

Adidas Terrex Swift Solo for me.   super lite and breathable open mesh upper and with stealth rubber soles. 

The only issue for regular all day wear might be that the stealth soles wear down too quickly if you're pounding the pavements in them 

Thankyou all - some very helpful suggestions to look into, that I will follow up and hopefully try some on.

Luke, the Evolve Cruzers look like an interesting option, but they seem hard to get hold of. Do you know of a current (uk) source for them?

I'm afraid not. I've never seen them in stock in any bricks and mortar stores but I've previously been able to buy them easily online. I can see why you're having trouble. Sorry I can't be more help. Hope this isn't a sign of them going out of production. I was planning to keep buying them every few years when I wear a pair out.

Cruzer slate classics half price needlesports £30 great price but i found the roof extremely low. Had to take the insoles out which obviously makes them uncomfortable, i use them for cycling

Also they're supposed to be really light, for descent. They're not that light, I've got lighter leather merrells which just happen to be that weight. I think there's a gap in  the market for genuinely light descent shoes with strappy sandal-like top and just a tough sole and toes protection. Could be a fraction of the weight