The biggest problem with platinum plugs is the small center electrode which makes a thinner spark. This effects idle quality.
I have seen a few posts on this subject in the past that elude to the platinum plugs breaking and destroying motors. I don't know anything about that though.
Before I found Mshop, I ran a set of platinums in my M103 probably 80,000 miles or so. I'm a little ashamed to admit that publicly, but the truth is the truth. I do have better idle quality now with a set of Bosch copper cores set at .038.