The way the Cheung-Bauer list was compiled certainly hard to see how most of the characters would be in widely known.
I'd need to look at C&B again for accurate numbers, but to some extent it's simply because some syllable-morphemes are listed with many different attested possibilities. So one really wouldn't expect to need all ≈1000 characters in there.
There is a tricky aspect to this, though: the left-addition of "o" (or a mouth radical) leaves the exact number a bit open and allows for a larger count. Do you write some Cantonese-only syllable-morpheme as "X" or "⿰口X"/"oX"? (Most of the latter combinations are in fact in C&B, but, anyways, it's hard to give a precise answer to the "how many Cantonese characters" question.) Here is an example: 嚿 vs 舊 for the measure word gau6 ("lump"). Depending on whom you ask, you might even find a strong opinion. Most people will probably say that "嚿 is better", but the fact that you find 舊 (because it's more straightforward to type) means that in a way it's descriptively correct. There are cases where the variant without a mouth would be regarded as more common or natural, because the version with a mouth radical is typographically rare.
With Zhuang Sawndip I have examining texts from different locations and eras, that there exists both evidence of transmission from generation to generation, of progression and also of unstability.
Just curious: what is a rough character count? Stephan
