I've been to many tastings (as is probably evident from my screenname) and wouldn't hesitate if you have the opportunity. The fact that its out of Riedels means that they are taking care to make it a good experience. One word of advice, you might want to bring a spit cup with you, as tasting that many wines will require spitting if you are to really appreciate them, and there are often lack of spittoons at events like this.