Harbeth P3ESR+Linn Sub or Bigger Harbeth Speakers

I currently have an all Linn stereo music system which consists of the Linn Akurate 4200 power amp (4 x 200W), Linn Katan bookshelf speakers (Linn active configuration) and the Linn Majik 126 powered subwoofer. My listening room is untreated and is roughly 12 feet x 14 feet (3.6m x 4.2m) and the speakers are roughly 7 feet (2m) apart and roughly 9 feet (2.7m) from the listening position, toed-in to point to the listener.

I love the Linn sound but find that the speakers are currently my "weak" link. I feel that there is more detail and dynamics that are being produced by my system but not being delivered by my speaker system. I came across this conclusion when I heard an exact system at a dealer but in a bigger treated room and with bigger floorstanding speakers (Linn Akurate 242 speakers).

I'm no sound engineer (just a music lover) so I'm not sure if this is really due to my speaker system or the fact that I have a smaller untreated listening room. My wife is against those ugly room treatment solutions so I've compensated by adding additional furniture, carpeting and a thick curtain behind the listening position which really seemed to help.

I've heard great things about the Harbeth speakers (Radial mid/bass driver) and later in March I will be attending the Montreal HI-FI Show (Salon Son & Image) to see if I can get a demo of some Harbeth speakers. After the Montreal HI-FI Show, I will be meeting with a local Harbeth dealer to audition the Harbeths in a more private setup with the possibility of doing a home demo once I've narrowed down my choice to 1 or 2 models.

Since I already own a Linn Majik 126 powered subwoofer, would it make sense to keep it and get a pair of Harbeth P3ESR speakers or would I be better off getting rid of the subwoofer and going with a bigger Harbeth speaker (e.g. Harbeth Compact 7-ES3 or Harbeth Super HL5)? That is, will keeping the Linn subwoofer and getting the Harbeth P3ESR provide the same results as my current Linn speaker set-up?

Linn Majik 126 Subwoofer:
http://www.linn.co.uk/files/a08623f4/Majik_126_Loudspeaker_Product_Information.pdf

Linn Katan Speakers:
http://www.linn.co.uk/files/6091d8c7/katan_user_manl_pack474_rev9.pdf