Elias,
What a timely subject. I removed and replaced all of my Rutgerson clutches just last week. Many of the screws were stubborn and wouldn't come out. Fortunately, stainless is fairly soft and I was able to drill through the screw heads and remove the clutch. The 1/2" stub was able to be gripped with a vice-grip and then removed. I was not completely successful, as several screws snapped off nearly flush with the gelcoat.
I filled the old holes and ground the old screws flush with the gelcoat, sealing all of them with epoxy. I mounted new Spinlock XTS clutches, which I am very happy with now. The screw spacing on the Spinlock clutches is much different than the original Rutgerson's, so new holes were drilled and tapped. Problems solved!
Cheers,
Jake