I drive a 2000 Type SH with the ATTS differential. It's almost entirely seamless but you'll notice it during any hard driving.

Does it improve handling? Well, it does reduce understeer but if you are skilled at handling a FWD car you will find it's limits soon enough. It can be a little slow to respond at times, which is readily apparent (I've heard) on a slalom course.

I didn't know as much about the car when I bought it. In retrospect I think a Base model with an aftermarket LSD added is better for an enthusiast.

If you just want a nice, fast sports coupe to drive and you don't race or modify beyond tires and brakes then the Type-SH is a great value and you'll probably be very happy with it