[Planeswalker]

Hi All 
 
I am looking for a pair of on ear headphones / IEM to replace my Audio Technica ATH ANC3 (AT) in ear ones.  I have very little knowledge and thought i would check out this wonderful site however i am now even more confused !! 
 
Basic Information: 
 
1)  Will be used mainly out of the house on either train/planes, however i very rarely used the noise cancelling feature of the AT as i like a little outside noise coming through
 
2)  Smallish, lightweight and portable 
 
3)  Have about £300 to spend 
 
4)  Musical taste (or lack of)  i actually like a very wide and varied selection of music, however currently on my main playlist is as follows: 
Passenger 
Mumford and Sons 
Bob Dylan 
Royal Philharmonic Orchestra
Bob Dylan
Green Day
Rihanna
Ingrid Michaelson
Lady Antebellum 
 
Tried Already and think i need an ear test !!
 
I have heard the B&W P3 but to me sounded very muffled compared to the AT (this again might be my lack of knowledge and maybe that is how they are supposed to sound) have also tried the PSB M4U2 which i really liked but the size was simply too big for everyday use.  The P3 were a great size but i wasnt sure about the sound, unfortunately the guy in the shop couldnt really advise if that was normal or not.  
 
I would like to get a shortlist of 3-5 then i can try and go out and have a look, i assume that there is no chance of testing an IEM so whatever comes back in that regard will be gospel. 
 
 
Thank you all in advance 
 
 
Cheers 
 
 
Zack