Fair enough. I have certainly done the dance with switching lenses before getting to my 28-70L...but as you can tell, that was a long time ago. The trick is figuring out how to incorporate the vari-nd filter, which is a very specific and not an inexpensive purchase.

My gut tells me that I would wait a bit and figure out which lens you will use more often. My goal historically has been to have enough of an arsenal of over-lapping lenses that if one breaks that I can use another...but I only use 5 main lenses. My 16-35L, 28-70L, 70-200L, 50mm and 120-300 F2.8 OS.

As most of the lenses are 77mm filter sizes, I am able to bounce between them rather easily. I am curious to see what happens after you purchase the 24-70. My guess is that your 75-300 may be the next victim (if it is the F4-5.6).

Also, have you considered the Tamron 28-75 F2.8? It is by all accounts an excellent lens and also uses a 67 mm filter size (if you plan on keeping the 75-300 over the long hall).

James