I can't be the only one that reads those two examples very differently.
In a first example, the second "occasionally" is stressed, when in second example it feels almost whispered.
Interesting, I read both as emphasized. To me, the parens make the voice clear but the em dashes make it read like a typo.
Interesting, I read both as emphasized. To me, the parens make the voice clear but the em dashes make it read like a typo.