Clovis

I've had the Tein RAs for about 30K miles now. I probably have about 35 autocross on them. On the street I think they are fine. Not as harsh as you would expect with such a drastic change in spring rate. Personally, I think the stock springs are way too soft anyways.

On the track/autocross is where they shine. Bringing the front rates up does in fact tame the rear of the car down. It also allows you to run a wider tire on the front wheel if you want. I currently run a 225 and 245 Hoosier setup and the control is noticably better. Many others who have driven my car always comment at how much sooner they can put the power down coming out of corners. Some understeer in the low speed stuff but I find it makes me so much faster on the high-speed corners and transitions. The dampers are also sensitive to change so you can dial in and out a lot of the under/over steer turn in with just a couple of clicks. With the variety of surfaces I race on I've found a nearly ideal setting for each. I'm not sure I've seen anything better for the price.

S2k_fever

I have them and love them. Car is much more neutral. The handling is much better. Ride stiffness can be adjusted very easily. Springs are 10k.
I say go for it you won't be dissapointed. The ride is not that harsh on rough roads if you put it on the soft setting.

StinkyTofu

Tein RA coilovers = The best mod i've done to my car yet.