I'm looking to pick up a filter holder for long exposures with an ND grad. I currently have a set of Lee .6 and .9 hard and soft ND grads, plus .9 and 1.2 Singh-Ray reverse ND grads, all 4"x6", which I've been handholding. I'd like to be able to shoot with an ND grad, standard ND, and circular polarizer all in place on an EF 17-40mm or an EF 70-200. This is where it gets complicated. Lee holder fits my current filters, but the combination of those three filters at once looks like it will push me to 20-24mm on the lens. Correct me if I'm wrong, but since I almost always shoot with a polarizer on anyway, my resting lens condition can be with a polarizer on the lens threads (B+W XS-Pro in the case of the 17-40), and a Lee adaptor screwed into the polarizer. Mount the filter hold, add the ND, adjust the grad, shouldn't get vignetting. Read something about needing to polarize the light before it hits the NDs; I call BS. I think it's a way for Lee to justify their idea of placing a 105mm filter at the front of the setup instead of closer to the lens like on the Cokin setup.
Other alternative I see is to go with the Cokin X-Pro, sell my existing six 4"x6" filters, buy three replacements (.9 hard and soft, 1.2 reverse) in the X-pro size, and drop the cash on Cokin's polarizer for that setup. No concern about vignetting there, and I can leave the adaptors in place on the lenses without the polarizer also attached.
Anyone have any thoughts? Anyone been down this road?