Yes, as you said, I guess there's not a much delay if we don't pay RPRF upfront.Its when you pay the full fees including RPRF when you submit your application. You have the option of only paying half and paying the rest later like JPV did. The advantage of paying only half is so that when they ask for the remaining money, you know you have passed eligibility. The disadvantage is that you might lose a few days... but clearly in the speed JPV is going...a couple of days dont matter!
The main advantage is one which I'm having at present, being aware of the fact that yes a human is regularly checking on my file!