I don't think Creative EP630 will be what you are looking for. It has the opposite of all the criteria that you listed. You might want to look at Meelec IEM like M9 and M6. 

I just recently got a pair of M6's. As I am fairly new to this community and unexperienced with different sound sigs, I can only attest to the isolation and comfort of these phones. 

Isolation - I had them on this morning and was amazed that I can barely hear the subway train as it pulled up to the platform, I was about mid volume on my player.

Comfort - I have never used iems until these but once I got a proper seal, I barely noticed these.  I usually only have them on for about an hour at a time, but I definitely do not see these getting uncomfortable during lengthy usage. Of course I did need to do some fiddling around with teh memory wires but once I got them set up, it was smooth sailing.

Like the above guy, I'm a noob to this stuff too, but I have to agree with the first reply, the EP-630 is NOT what you are looking for. They have next to no treble. They are pretty comfortable though. I am not sure I would recommend the M9 and M6 either though. While both have a comfortable fit, the sound wears on my ears and make we want to take them out after half an hour of listening. That's just me though. Also the mids are recessed which bugged me since I like vocals. Still working on training my ears, but the I believe the mid-base could be described as "big," but I would get audiophiles opinion on that. I just got the M11+ in the mail today though and have to say the mids sounded a lot better and hopefully burn in will only improve that. Probably the same as the M9/M6 in mid-bass. And talk about comfort, they are so tiny could not feel them at all. Since Meelec has been running them in their daily deals for under $30 lately it might be worth considering. 

If you are looking at the PL-30 then I highly recommend its newer sibling PL-50, it is apparently one of the most comfortable phones rated here (and also backed up by my friend's experience) and is fairly balanced.  I will third that EP-630 is not the droid you're looking for, although they were some of the most comfortable IEMs to me because they are very light and had perfect fit for me

If you can increase the budget to $80 then I can suggest you Sunrise SW Xcape. This IEM sounds exactly the way you describe. It has sparkling treble but not harsh (depend on the source also), smooth mid (sounds great with female and male vocal: Diana Krall, Norah Jones, Eva Cassidy, Dave Matthews, etc), bass that is tight and punchy but can rumble (hip-hop) if the song called for it. It has the most natural sound from my IEMs collection (Denon AH-C700 and C551, Mee M9 and M6).