The whole idea of speedy boarding was designed for 'no frills' airlines where seat reservations were not possible. When I booked flights for me and my two young sons there was no obvious indication that seats could be reserved so I chose speedy boarding. When I completed the online check in 5 days before the flight was due to leave I saw that most of the seats had been reserved, rendering speedy boarding redundant and useless in terms of advantage.
I have every intention of making a legal claim against Ryanair as I expect something for my money and it looks like I will get no advantage at all from Speedy Boarding. It seems to me that Ryanair's speedy boarding is a scam.