Well I must be nuts then, as I had an F-75 and now have 2 Coinstrikes, which I so far prefer.
Not sure why you are looking for a comparison since you don't sound interested in the Coinstrike, unless it's to justify an F series purchase. If that's the case just hunt with it and forget the CS - both are capable.
As far as ergonomics go, I find them about equal. I don't feel the Coinstrike is heavy, though others do. The F-75 is great. Build quality goes to the CS. Target separation boy that's tough, both are great. Very fast. Depth again both go deep. The notch system on the CS is FAR more logical and easy to use than the one on the F-75 - most people don't even know how the one on the 75 works, I had one and I don't know how it worked. I just left it alone, it was so convoluted. Both have backlights, the CS has ground tracking the 75 doesn't. Both have a decent selection of aftermarket coils. With the CS you can save and recall your settings, while with the 75 whatever you are using is what you've got. As far as target ID, this is just my opinion, but it seems to me the classic digital Fishers (EDGE, EXCEL and CS) have a number system that is a little to learn and feel confidence in the ID. But the 75 is not bad at all. Both seem to like rusty bottlecaps.
As we go through this, there are a lot more ways they are similar than not. To me the sound from the CS is even much like the 75. As I said I'm nuts so someone will probably pipe up screaming to pull my head and my ears out and I'm full of it. Can't please everyone.
I honestly prefer the CS. Recently I picked up 2 of them for less than the cost of an F75, brand new with warranty (the same 5 year warranty that the 75 has). I wanted to try them out for myself while I could still get ahold of one. I'm looking forward to what it can actually do out in the field. Like I said, I really think they are very similar machines, though I prefer the trigger that the 75 has to pinpoint with to the button on the CS - they really should have used a trigger for that. And those touchpads are as you mentioned touchy, literally. But you get used to that as each machine has it's own quirks the 75 had it's own as well (the notch system, and the fact that some settings radically change performance on the machine and these settings aren't obvious).
Both are really sensitive to EMI. Like I said, very similar machines. I don't think a person could go wrong with either, I so far prefer the CS, but if I had a 75 again, I would be very happy with it as well.