@Doitsu...My apologies to you for doubting what you said about "Enhanced Typsetting" enabling KFX. I've just re-read JP Howell's post which does confirm that when "Enhanced Typsetting" is enabled then this effectively means that KFX is also enabled as you said. Notably, when I went to
Kindle Jumpstart's Enhanced Typsetting description page, there was no mention of KFX conversion being enabled when "Enhanced Typsetting" is enabled. Hence my doubt and my confusion over this.