Hi all, this is my first post so I would like to start by saying a big HELLO to everyone 
I have recently purcahsed a mkII 5D with 24-105 lens. I also own a 30d and 40d. I wish to keep the 40d as a backup camera and sell the 30d along with some lenses which I dont use much.
I shoot weddings and portraits and have found my new lens (24-105 L) is great as a general work horse. I do however wish to purchase the 70-200 f2.8 IS USM L lens for more candid stuff and low light situations and use these two lenses for most if not all of my wedding work.
Here are my questions;
1) How have you guys found the canon 70-200 IS USM L lens in terms of optical quality and low light performance and was it worth the hefty price tag compared to other lens from tamron and sigma?
2) Which lenses would you hold on to from my list below and why? I have put my choices and why.
My Canon Lenses:
17-85 EFS IS USM (5.6) - Out, only works on crop sensor camera
70-200 EF (5.6) - Out, wouldnt need it if I bought the 2.8l is USM
80-200 EF (5.6) = Out, same as above
70-300 EF IS USM (5.6) - Poss Keep?, extra 100mm
10-22 EFS USM (4.5) - Poss Keep? only usable on the 40d but super wide
35-80 EF (5.6) - Out - my 5d kit lens covers this
50 EF (1.4) - Poss Keep? - cheap, f1.4, great little lens
I know its a bit of a read but your advice would be much appreciated.
Thanks in advance
Khani

I have recently purcahsed a mkII 5D with 24-105 lens. I also own a 30d and 40d. I wish to keep the 40d as a backup camera and sell the 30d along with some lenses which I dont use much.
I shoot weddings and portraits and have found my new lens (24-105 L) is great as a general work horse. I do however wish to purchase the 70-200 f2.8 IS USM L lens for more candid stuff and low light situations and use these two lenses for most if not all of my wedding work.
Here are my questions;
1) How have you guys found the canon 70-200 IS USM L lens in terms of optical quality and low light performance and was it worth the hefty price tag compared to other lens from tamron and sigma?
2) Which lenses would you hold on to from my list below and why? I have put my choices and why.
My Canon Lenses:
17-85 EFS IS USM (5.6) - Out, only works on crop sensor camera
70-200 EF (5.6) - Out, wouldnt need it if I bought the 2.8l is USM
80-200 EF (5.6) = Out, same as above
70-300 EF IS USM (5.6) - Poss Keep?, extra 100mm
10-22 EFS USM (4.5) - Poss Keep? only usable on the 40d but super wide
35-80 EF (5.6) - Out - my 5d kit lens covers this
50 EF (1.4) - Poss Keep? - cheap, f1.4, great little lens
I know its a bit of a read but your advice would be much appreciated.
Thanks in advance
Khani