Had a few sociable beverages yesterday and two of the group I was with used the bus to get there. 
The 4 was brought up and those 2 who used the bus, could have used the 4 to get to our rendezvous point.
They both voiced concerns about the length of the journey now the 4 has been diverted (or the apparent length - I imagine it is similar to the Coast Road effect with the slip roads and it seemingly taking longer than it actually does).
Anyway, to cut a long story short, neither used the 4 there or back. One even arranged a pick up from Heworth on the way home.
Is the diversion of the 4 and apparent success of the change for Amazon workers, sustainable over the apparent dissatisfaction of regular customers? 
Granted it was a small sample (remember that discussion eezypeazy - guessing you may still lurk), but it would be interesting to see what impact the diversion is having and what other regular passengers on that portion of the route actually think of it.