> it is hardly used except for the word of foreign origin.
But in 2ch, it is frequently used, so, 2ch slang is more colloquial.
For example, こっそり(kossori) in Japanese, it means "in secret". But in 2ch, sometimes be used ｺｿｰﾘ(koso-ri). In 2ch, half-width katakana with prolonged sound mark are preferred.