I am old fashioned in lots of ways. I, personally, don't think that sole guards make much sense. But my wife likes them. And sometimes she convinces female customers that they will like them too. I think that if you want rubber outsoles, go for rubber outsoles.
I wear leather in all kinds of weather.
With regard to heels...on boots, I mount a full rubber toplift, unless otherwise requested. On shoes, I generally make, from scratch, a combination toplift--1/4 rubber, 3/4 leather...or whatever ratio looks good to me that day.
Everybody has an opinion on this. Here's mine:
Functionally, rubber probably has the advantage over leather esp. in wet conditions although even the newest, most advanced rubber compounds can slip on polished or slick surfaces...as badly or even worse than leather. IMO.
Aesthetically, rubber outsoles bring the whole shoe down several notches--an $1800.00 shoe suddenly looks like a $500 dollar shoe. And no one looks twice. IMO.
Ethically, rubber is petrochemical and has done more damage to the environment since the 1940's than veg tanned leather has in its entire history--roughly 10,000 years. IMO.
That's my opinion...no charge.
Again, I find this all very helpful. I probably need to trust my leather-soled shoes more. Soon, I'll be wearing them in brine slush after snow storms. :-)
One quibble on the rubber: there is natural latex rubber, which I don't believe involves any petrochemicals, but I am frequently wrong...