So I just installed this and thought I would post my thoughts. Pictures to some as soon as I get them off my camera.
Install took me about 2 hours total. This was by myself and with a lift. Having a buddy would certainly help as there are several steps that alternate between in the car and under it. Having the extra person would save having to raise and lower the car multiple times.
This is the third UUC SSK that I have installed. One in my E46 330i and one in a friend's E36 M3. This was easier in some parts and harder in others.
In general, getting access under the car is the trickiest part. There is one plastic panel under the tranny. This comes out with a few screws. The tricky one is the aluminum heat shield above the exhaust. This is where if you are going to replace the exhaust it would probably be simpler to remove that to get to the heat shield. Since I was not replacing the exhaust I left it in place. What I was able to do was unbolt the heat shield (luckily there are several smaller sections) and gently slide it backwards about 6-8 inches. This created enough access to the shifter area without having to drop the exhaust. Just be careful as it would be pretty easy to bend or rip the heat shield.
Once the linkage was disconnected and the old shifter was out it was time for the bitch clips. These were surprisingly trivial. There are two of them but they are lower and you can actually see them to pry them out.
With the clips out it was time to remove the carrier. This turned out to be trickier than expected and in the end I didn't actually remove it. Supposedly you can slide the carrier forward so it comes out of the rear bracket. No luck with that at all. The top of the tranny kept getting in the way. I even tried loosening the tranny support a bit for some extra clearance but no luck. So I installed the pivot relocation cup with the carrier still in the car. With the clips removed there was enough play to get the screws in from inside the car. I did cut off about an inch from the long end of the allen wrench so I could get it in there. Requires some nimble fingers but it is doable.
Reassembly was straightforward. I left it at the stock height for now and I'm using the stock shift knob. I had the RK5 in the 330 and liked the extra weight but I think I'll stick with the stock one for now.
All I can say is that I have been waiting for this ever since I got the car and I am not disappointed. Coming from the 330 with the SSK installed it almost felt like I was rowing a boat. Now shifts are short and crisp. There is a little notchiness going into first and second but that was there with the stock shifter as well. I'm still under 5k miles so I expect that to smooth out a bit. The wife took it out and said it was "fun".