JL F is one of the few F products which I will occasionally pay out of pocket to get with excitement and as a result one of those I experience notably on that route. When OP says that 'flights are typically rammed' this is true but certainly includes F where I have rarely seen an empty seat (there are only 8 to start with as noted) so frankly, chances of upgrades are minimal and if they occurred would indeed certainly benefit either VIPs or JL's own highest tier members.