jmilo said:
hmmm...i thought 4p got more bass...or maybe you haven't got the right fit yet...
Although both 6i and 4P got enhanced bass compared to 6 and 4S, 4P dun really have more bass than 6i. Its got to do with the seal and depth of insertion. I've been playing around with the various tips for the past week and with Shure's small clear flex, i managed to get close to the amount of bass that i can get from the 6i.
(Insert real deep!)
4P got deeper bass at softer volumes but not more unfortunately. Using them outdoors is really a hassle and a pain. Its slightly superior isolation (compared to Westone/Shure) don't help actually. While ambient noise don't drown out its bass, the cord noise and the louder footsteps (Felt like godzilla!) due to more isolation drowns out its bass. You can still hear some bass, but no longer as clear cut.
I'm trying to write a review. I think got quite a lot to write but lol lazy.
But I've taken down notes for the comparision with the 6i before i sold it.
Its a different flavour to the UM2. I think you should give them a try. ER4P is good for different moods and setting. For example, if you're in a relax and lazy chilling out mood, the ER4P will be at its best while the slam and impact of the UM2 will give you a rude shock. But if you got your adrenaline all pump up and want to rock/party on, the ER4P will fall flat as it lack UM2's slam and impact.
Like most people, they got different cans for different moods. UM2 is a little like a Grado/Alessandro (Got lots of impact) while the ER4P is more polite, more like a HD555. (Refine but can be boring at times)
(I think the text in this post can recycle for my review lol)
Did some comparision against the ER4P. 6i got more bass! 
I managed to get more bass out of the 6i than 4P. Maybe i'm still struggling with the fit of 4P. But 4P is more revealing.
