Some countries (Malaysia, that I'm familiar with) actually have notes of a different physical size within the country. For example, the dimensions of the five ringitt and twenty ringitt note are different. I believe this is what the GP was referring to.
This implies actually knowing Braille. Even in very developed countries, not all blind or visually deficient people know Braille. Arguably, they should be pushed toward Braille rather than left in a "comfort" zone.
There are many ways for Braille to fail, particularly if embossed on a regularly-used banknote, and not everybody can use it. Differently-sized notes are much harder to break, and are potentially useful for everyone. Make the notes differently-coloured as well, and they're straightforwardly distinguished by most people, regardless of disability (or lack thereof), in a variety of situations.
(I would imagine Braille costs a fair bit to print, but banknotes are somewhat expensive to make - compared to most pieces of printed paper, I mean - so perhaps that wouldn't be an issue.)
Aesthetically I love how the £50 note looks, in part thanks to its size, but it is really annoying. I guess most people don't often really come in contact with it, but anyone playing in a casino is likely to get them when cashing out, and they stick out of my wallet just a little, but enough to annoy me. And if you're cashing out a decent sum, asking for £20s isn't really an option,too many notes and the wallet won't even fold over.
