ER4S is pretty much flat, those who measure various IEMs and do monitoring pretty much establish it as such for a reason.
It is, pretty much. I do think more would use a UERM than the ER4 professionally and it has more bass to my ears. As you know I have no issue w/ deep insertion, that's how I roll. I get more midbass from the dBA than the ER4 but DBA's lack extension by comparison. I also find the ER4P to sound rather boomy at times and sharply bright though they don't seem to graph much different from the 'S'. 'S' I can listen to endlessly, 'P' kills me in less than 2 minutes. There is also an unfinished debate about what truly neutral bass at the ear should graph like though the deviation is rather small. Same for headphones. It's actually very complicated and goes beyond FR so we should probably avoid it here.
A V-shaped response isn't always bloated like the HJE900s or even the TF10s case, these are an example of that.
That's what 'U' curves are for. I'd still need to reproduce more bass on the EX1000 to agree but I understand what you are saying and hearing.
Not sure if I remember, but did you hear my GR07 or joker's? There's a difference between the two.
I don't recall, but it was a bit bass boosted, treble harsh, unrefined and not reference to my ears. It had that bio-cellulose 'attack' and flavor to it.