yes, the ZZP modded 1.9s are on my car. they work great on stock valve springs.
The hell they do... I have a broken stock spring in my garage from running my Intense 1.9 rockers. I was only shifting at 6k too, never any higher. I ran the rockers 60,000 miles before the spring broke. The WASN'T a fluke deal either, there are several on ClubGP who have had this happen too with much lower miles on there rocker setup.

Don't halfass it, if your gonna buy rockers do the springs/retainers too... unless you want to drop a valve. While you're in there you might as well replace the seals too...