I started out on Apache 1.x, and after upgrading to 2.x, I decided I didn't like it.
I don't remember the exact reason, but for some reason, I just became frustrated. Perhaps it was because it was something new, and I hadn't experienced problems with the old version.
Thus, I downgraded back to Apache 1.3 and left it alone.
This is only personal testimony; others may feel strongly in the opposite direction. As long as you keep up-to-date with upgrades/patches to the Apache 1.x series, I don't see why you couldn't keep it. If you're looking for new features that Apache 1.3 can't deliver, then you could hunt around on Apache's Website for new features, a changelog, etc.