Negative view on FIRST:
I think the paces look a bit racy - if I followed the detail in the plan of a session a week at 45s faster than 10k pace I'd be at 5:30 miling for reps which is fine for short bursts but they build to 3 x 1mile - I think that'd break me. There may be more subtleties in the book versions of the plan but at first glance this seems a bit too much for me.
2hr bike then 3k swim last night
5hr bike this morning - 85miles and 5000ft of climbing
Bike and long run in the schedule for tomorrow morning