I would slightly rephrase the part about "no sleeper service in F". It is more the case that in F, you only get sleeper service in a good way, ie you do get pre-flight dining before the flight if you so wish (which is an advantage, especially as it is usually proper sit down quality dining) but you still get full service onboard. The only exceptions are flights ex-JFK and IAD which get all day dining in the CCR.