I haven't been to Frontsight but know people who have. From what I hear they offer excellent training.
I probably won't be taking any classes there. It's just that I think Prescott, Arizona is a nicer place to be than Pahrump, Nevada. So I'll probably stick with going to Gunsite.
But if you have a chance to get training and it works for you to get it at Frontsight, do it. I'm a firm believer in training, and from what I've heard, you'll get good training at Frontsight.