I was able to look at one up close when I was at Cabelas about 2 weeks ago.

The concept looks pretty cool, however I don't like the fact that the inserts weigh so much. I already have to shoot a .340 spine arrow to get it to spine right for my bow. If I added 35gr to the tip of my arrow, I would need something like a .300 spined arrow which in addition to the extra 35gr from the insert, the arrow would be mucho heavy and slow.

I think you would be better served with a Whisker Biscuit and save like $100 to boot.