EG advise against Topy rubber soles

Of course, EG would have nothing to gain by issuing that warning.

JM Weston say the same thing citing the inability of the sole to "breathe".

my wallet needs to be emptied constantly for it to breathe

FACT ..I do like ,as always, to receive different opinions before taking a decision on the matter and every source(from Berluti ,John Lobb to informed professionals) was reaching the same conclusion:The rubber sole being hermetic does not allow the leather sole to breathe.....
But they all agree that no choice is without consequences...
Even if It is true that they all have a certain commercial interest based on the constant need to partially replace the leather sole they have pointed out the fact that we have to choose between two evils...
Paying the price for walking on leather or potentially damaging the sole...

...or slipping over and landing on the seat of the pants of your bespoke suit.

That's three evils!!!!!!!!!!

Why not just get them resoled with rubber soles and avoid all of this to begin with?

May I defend the opposite view ? IMHO, rubber soles are bad for the overall aesthetical balance of the shoe, they make it look heavier and bulkier (specially for shoes with a thin sole such as EG - it's part of what makes them beautiful and unique).

Moreover, I would tend to believe the explanation about leather soles having to breathe. But I recognize that's more of a debating point.

Finally, when buying a pair of EGs I see it more like an investment. Would you buy an expensive car and not service it accordingly ? I wouldn't. Similarly, I know I'm wearing pricy shoes and the 'service' of those shoes is going to be pricy as well. In other words, I don't have problems with the idea of sending them back to EG (even if it's expensive) to be resoled, provided I receive impeccable service and as-good-as-new shoes in return.

Finally, I'm living in a city and mostly walking along streets in a rainy climate, but I don't find leather soles to be so dangerous to walk with (that is, once they are a bit worn, because walking with new leather soles can indeed be tricky -but that's a 3-days problem).

I tend to agree.

I have had the Toppy sole added to a couple of shoes, and they just aren't the same. They're a hybrid between leather (dress) and rubber (sports) shoes. The rubber adds somewhat to the thickness of the sole.

However, the rubber makes the shoes pretty "slip-proof". But, I have found that worn brass nails in the heel make the heel very slippery. When the brass nails become worn and flattened I replace the hell with rubber.

I must say that, when I was selling shoes, I saw a LOT of old, Topyd (is that a word?) shoes...lots of old people where I live, and we get lots of snow and ice. I don't recall a single one whose soles had rotted from the breathing issue.

Funny, Tony G. recommends a thin rubber covering over part of a leather sole, even on bespoke shoes, and does not believe it causes any problems. If done right, you can't tell there is any rubber there at all unless you turn the shoe over.

If you wish to best preserve the breathability of sole leather, simply use the rubber to recover the seat of your pants.

I've had many, many shoes Topy'd over the years, although none of my best-quality dress shoes. I don't bother with Topys on my EGs or Lobbs because I wear them relatively infrequently and am not worried about wear (although I am somewhat worried about slipping and falling on my keester). Pretty well all my Allen-Edmonds, Ferragamos, Ballys, and a few C&Js have had Topy rubber sole covers. This goes back more than 25 years and has involved perhaps 25 pairs of shoes. Not ever has any sole damage occurred because of a lack of breathability; it's just a non-issue, and, in my opinion, is based more on (incorrect) theory than on any empirical evidence--at least if my own "experiment" (experience) is generalizable, as I believe it is.

I've found that the Topy addition does next to nothing to degrade the appearance of the shoes, being as thin as it is, and, in fact, is all but invisible except, perhaps, when one raises his shoes to cross his legs or something like that. Further, the Topy does seem to render the sole virtually indestructible, and makes the shoe stable and safe underfoot.

Interestingly, this issue about the detrimental effects of covering a leather sole with a rubber overlay comes up about every 6 months or so on the forums. Every time, someone points out the (in my opinion flawed) theoretical argument against this practice (a lack of breathability leading to damage to the leather sole), but, if I remember correctly, no one has actually witnessed any sole damage resulting from it.