I bought a Summit Viper this year. It’s my first climber and I love it. The foot rest is a great addition. I'm 5' 8" and I can't imagine hunting without it. You taller guys would really need it. I also spent $8.50 on eBay for the High Traction Strips. After leaving it locked on a tree all one night, the platform was slick from frost and my feet nearly slipped out from under me at 20 feet in the air. I also added the side bags for all my gear. I'd like to add the gun rest for steadier shots.
I would change a few things if I could. The seat is a little short. After several hours in the stand, I've wished it was a little longer. Move the seat straps as far forward as you can just before you sit down. This will give more seat under you and make it more comfortable. Also, the frame is a little narrow. It’s big enough for my torso to fit comfortably but my arms don't fit inside it. This is uncomfortable after a while. Raise your seat up so that when you sit your arms will rest comfortably on the frame. If you wanted your arms to fit inside the frame, you probably should have gone with the Goliath or Titan.
Lightweight for backpacking
Simple to use
Very solid and sturdy
Lots of accessories
Quiet on the tree
Narrow seat frame
The Titan is larger so it probably does not have some of these issues. Overall, I really like the Viper. It's well worth the money.