Joe,
Your description of the F80 M3 sounds wonderful (and I do believe the F80 is the perfect modern day E39 M5, in size, with a huge number of improvements in every area of the design and function). Seriously, you lucked out, big time, with the arrival of the F80 just when you were ready to move out of the E39! What better new sedan could someone with a young family buy? None, imo, the M3 is it! When my first kid was born ~28 years ago, I bought the equivalent at the time...the highest performance 5MT sedan available in 1986, the E28 535i. What a difference compared to the M3, huh? Dang.
I would love to back-to-back drive the two M3s on the same course using the same tires -- sure would be a fun time. If you're ever in the area, stop by and you can wring out the E90 M3. It's mostly stock (SCCA F-street) with just a larger Dinan front sway bar and pins-out-up-front for max negative camber alignment. We can put the autox wheels/tires on it and really have some fun (BFG Rivals).
It would be fun to back-to-back compare the two cars. The S65 is ferocious when you keep it on the boil and actually not *that* much slower than the F80 up to 100mph (comparing C&D test data 9.0 vs 9.6 seconds for 6MT cars), but it is hugely involving. Where the S55 makes mountains of torque is definitely not the strong suit of the S65 though...by a long shot. Which makes the S55 a better all-around daily driver imo not only for effortless-torque-at-any-rpm but also improved efficiency, mileage in daily use.
Similar to the large differences between the F30 and F80, the E90 M3 is a wonderful car to drive properly compared to the other E90s. I've got an E90 330i 6MT with Bilsteins to use as a comparison too (fun car in its own right).
[up on soapbox]
Speaking of which...I really hope that EVERYONE who has bought an M3/M4 with its brutal amount of power all across the rev range, *and* who do not have extensive experience driving a very powerful RWD car, will be extremely careful when they turn off DSC the first time. In the old days of the E39 section of the M5board, it seemed like it was a once a week occurrence for someone to turn off DSC the first time and then wreck the car. I'm not speaking to you Joe specifically as I know you likely have great respect and care for driving with DSC off having owned the M5, but instead to every other owner who doesn't have a solid background in autocross/track/drifting/high power RWD cars but has gotten used to "driving" the F8x with DSC active and then turns it off the first time expecting to drive it the same way.
[/stepping down off soapbox]
Cheers,
Chuck