Is this the best way to predict your marathon race time?

[Matthew Rowley]

I'm not an expert but I have done the Yasso 800 and they were within 5 minutes.  I think the most important part is not resting too much between each 800.  As for all marathon predictor they assume a level of fitness. 

I would recommend the workout just for the sake of the workout.  I felt the workout was a pretty good speed work out.  The workout helps build speed.  The long pace felt easier after doing the workout.