Older articles exist - check Dirt Bike and Dirt Rider archives. At least three specific article tests exist based upon memory. The basic engine and drive train has not changed since 98: USD forks, triple trees, ignition advance curves, shock, hydraulic clutch, and swingarm upgrades have been made.
The "new" 98 380 likely in Sept - Dec 97 time frame. The changes for the 99 380 model as tested by 'Lumpy' over a 3 day 300 mile trail test. A shoot out between the open class bikes - comparison to CR 500, KX500 if my old memory is correct. Believe there was also a fourth article based exclusively on KTMs riding in Eastern Wood conditions.
My '98 380 EXC is a great bike - I love it for trail riding, hill climbing. and play racing with friends. If I was a serious racer I would opt for one of the smaller displacement models since the 380 can be a handful when on the pipe for an extended length of time through any sort of technical riding area.
IMO - articles on the 300 are also applicable to the 380 concerning fork and shock performance reviews since other than displacement related factors there are few handling differences.