As with a lot of things in life, more expensive doesn't necessarily equate to something being better, something I found with the oppo ha2 se which I hated despite it costing 100quid more than the dfr and both containing ess dacs.
As for the iems, I agree that fit is crucial. I always hated the apple phones when for that reason and was much happier when I moved onto the sony MDR ex650 which were about £50 at the time. They were a much better fit and the difference in the sq was immediate.
In terms of the difference between these and the heaven v's , I auditioned the latter with songs that I had listened to a lot during my commute and so knew really well. Across most of the songs (the only exception being Paul Simon -graceland), more detail, more "air"around vocals and percussion and more accurate placement of sounds in their own acoustic spaces. As I say above, they were a little bright but in combination with the dfr, the brightness was tamed with good results.