I'm not a power user, really entertainment, sub for TV. And photo editing hobby.(Love iPhoto editor)
I used Windows Explorer a lot and do miss it also.
My wife still has a PC. Her computer needs are about a 10th mine. IOW e-mail and card games.
She's switching to a Mac shortly. She doesn't know it yet though. :^)
So do I once I learned how it worked; it's one of the most powerful tools on Windows, and I would miss it terribly, can fly through my files with it. So it sounds like I'll be able to use explorer on the Fusion side of the imac but not the other. Sigh. I've even got an addon that lets me browse my photos in .CR2 format, it's a real treasure although there are other ways to browse. So sometimes it's just the little things you have come to take for granted that have a great impact on your workflow.
It appears we have some PC vs. Mac wars going. Reminds me of the Nikon vs. Canon wars. I refuse to feed into them because even to this day, sometimes I wish I had both systems because each one has its unique strengths and weaknesses. IOW both are excellent products.
So it seems silly to squabble over it because I plan to keep using both and am sure there are features of one that will outshine the other and vice versa. Given enough time, I'm sure I will gain a preference to one over the other but have a certain nostalgia for this or that.
Last night I went to bed not caring about the mouse, will deal with it. Then I remembered how dependent I am on the mouse for all my graphics work in PS where precision and sometimes freeform are critical. That will definitely factor in. I got a WACOM tablet which I instinctively feel I have to use left-handed. Being on a pc has really thrown me off. I got comfortable using the mouse right-handed. I could have configured it for my left hand. Now anything relating to computers, my right hand dominates while I still write and eat and do a lot else left-handed. Sports I do right handed except for throwing a ball I revert to my left hand. I guess I'm wired funny.