I've got a 135mm. Great lens. I've also got an 85mm 1.8. I chose the 135 over the 105, because the 105 seemed a little redundant in my lineup. Very close focal length to the 85mm.
I have the 105DC and love it. It's great for full length shots of baby's . I recently picked up a 180 but have not used it much. I borrowed a 70-200 to play with and as you said it was very heavy.
Josh has given a lot of good advice lately on how to decide what lens to buy. "Figure the pictures you want to take and buy the appropiate lens.'
I recently got the 135DC for the sake of performance/weight ratio. I was really close in getting the 180 which is a really good lens, but I was so intrigued with the DC option that I could not resist. Am I happy? Yes, but I think that the 180 is more what I need focal length wise. Other than that, the 135 is fast, sharp and bulit like a tank!
