My post was merely to clarify that (despite your initial comments in response to the OP) that the Chefs are in fact still in place.
Yes and as I said it depends on the route and the OP seems to be flying from JFK-LHR, so he will have the chef but the bigger point is that the chef doesn't make a difference to the actual food, it is simply a difference in the way your order is taken and perhaps more chances to customise your order.
Either way the thread is about the differences between F and J and whether the OP (who seems to have disappeared) should give more miles to fly F.