There's a certain amount of shock value attached to munching razors, to be sure - but I would consider the actual impact of the effect to be based more on cringes than awe.
I've seen this effect performed very close-up, and I was pretty grossed out by the whole thing. And there's a valid point made here about generations - younger folk may not even recognise them, as they are an object which is not familiar to most, I would presume.
Saying that, it's whatever floats your boat. I take it you've got the necessary props?
If not -
http://www.emagictricks.co.uk/product_i ... ts_id=2377
Do it properly, and you should still be able to lick stamps the next day...
Do it wrong, and you won't be able to eat M&M's without them dropping through your cheeks.