I last did this on 3 Feb and quite liked it even though it gets tough towards the end. After a poor night's sleep and a crappy day at work I was in 2 minds whether to do a workout to day or not, but I guilted myself into it knowing that I need to keep working hard to gain/maintain fitness ready for the race season.
The session went almost exactly as before until my Garmin Premium HR strap started to play up after 35 minutes. I don't have a lot of luck with these and they normally fail after 4-5 months and this one was no different. I was unable to complete the 4mins x 320W interval at around 46 minutes and instead converted it into 2 intervals of 2 mins at 320W with a short recovery in between. I think my HR data at this point was correct as the recorded 167bpm is usually where my body starts to whinge and moan about the effort and I start to think about quitting.