Let the hive mind of Engadget get that for you.
"I just switched to Sprint from Verizon about three months ago for the Pre. Then I went for the Hero about a week ago. Now, I miss my hardware keyboard and am thinking about switching to the Moment. I am still able to switch back to Verizon if I want and get the Droid when it arrives. Should I just trade up to the Moment when it comes out, see if I like it, and if not switch to the Droid? Or something else entirely? Help!"
And get this - the H4 will also function as a USB audio PC interface (essentially an external sound card). In this mode the sound output quality blows away my internal sound card.
I understand Paul's concern. I'm also trying to standardize around SD cards (Palm Tungsten T3, Treo 650, Zoom H4, Cannon digital camera, etc all use SD cards). I realize that in some cases I'll have to use other formats, but why not keep as many devices standardized as possible?