i was really going to go with the 50-150 F2.8 by sigma but went with the canon. although heavy, i'm sure it will be great. i'm going to use it for a wedding for the first time on jan 1st.....yeah, new years day. i will never shoot on a holiday again but i wanted the client. it's only for 3 hours though, which is ok......
it is a bit heavy but no problem for me. i also bought a sigma 30mm prime F1.4 i LOVE this lens! it's razor sharp! i have a canon 50mm F1.8 which is great but a little too zoomed in for me. the 30mm is great. i will still use my 18-200 F4 sigma lens for things when i don't want to lug the 70-200 around.
happy new year,
steve