I have had the privalige of owning a Mk1 RS and have taken the Mk2 for a test drive when mine was being serviced. To compare the 2 cars i was mildly disappointed with the Mk2 it did not move the game on as much as i was kind of hoping.
As soon as i started driving the Mk2 it was like someone had put an extra sumo wrestler in the car, it felt heavy. Very grippy at the same time mind. The Mk2 shape of focus always seemed long and it really is. Torque steer is still present even though it has the Revoknuckle and does have a great sound and a good turn of speed. For me the main improvements were the interior and the sound. I still felt my Mk1 handled that bit better, it is roughly 200-300kg lighter i believe and definitely felt it when blasting around.
All that said, I would still own a Mk2 for sure as a family car as it was bigger than the Mk1. Although Ford do impose an RS tax on servicing etc and there have been some problems with the Mk1 and cost me alot of money to fix. So i reckon we need to wait a few years to see if the Mk2 has a better build quality.
Mk2 compared to Zed, i'd still take the Zed everytime. But they are 2 completely different cars. The Zed sounds better for me and has better quality of materials and feel inside, plus RWD means you can use all 300 rampaging horses without any torque steer (The Mk2 does also limit power in the first 2 gears to help with the problem). Nissan gave me better service at the dealership too.
Hope that makes a good read