I have a sumit viper X4 and I love it. I feel 10 times more secure with the bar infront of me and it works great while climbing. My hunting partner has the summit cobra and it is very comfortable but I feel like i'd fall out if I fell asleep. The viper also works great as a gun rest. With the viper you have to lay the gun across your lap I also worried my guns going to slide off my lap one of these days.

Summit makes a model called the Goliath that I'd look into. it's it's $100 more but IMHO it's woth it.