A friend of mine recently loaned me some Ergon R2 Magnesium grips to try out. I put them on my 29er Single Speed (Soma Juice). The bike has a rigid fork, so I thought that the Ergonomic shape of the grips would provide a bit of padding on my hands. Also, although I don't like bar ends, there is something to be said about them for their hand positions - especially when you are climbing a fireroad on a single speed.
In the past month that I've had them installed, I've ridden them on quite a few rides - mostly in Forest Park and I really like them as they did help pad my hands - providing just enough to take the edge off as well as take away unnecessary pressure.
The exception to this, is I had them on my bike for the first Short Track Race. If you read that report, you'll notice that it really wasn't my best showing. I kind of blame the crash on the grips. At the start I was neck and neck with the front of the pack. The bar ends seemed to have gotten caught a couple of times on other riders and I think ultimately resulted in me losing control.
So, in summary, these are great grips, just don't to a tight fast race with them.