I used to think coil-overs for road use, even fast and aggresive road use was OTT. But after having lived with my IV on everyday driving (no time to go to the track lately) with TEIN HA's, I would say yes!!! No other mod is worth so much yet delivers on the promise IF it's tuned right / properly.
After about 4 mos. diddling with my suspension, I finally got what I wanted: a wee bit overly firm ride, no bounciness, fantastic braking and always feels confident on the road, however bad the surface is or the weather conditions are. Much much better than the OE suspension.
Make sure that the coilovers are suited to what you're doing - esp. if its road use don't go for too high spring rates as it won't work well on your average British assualt course type road. Probably no higher than 70/60 for road use.
Also I reckon adjustable top mounts (ie rose jointed) might make it a bit harsh on the road - they are usually track options. You can always firm things up a bit with Grp N rubber topmounts (unfortunately not camber ajustable)