I've only used a Bullet Backpacker Summit..


Pros

Safe

Quiet climber ..I can be absolutely silent climbing and unclimbing..the cables are rubberized.
Can stand and shoot nearly 360 degrees.

Pretty darn comfortable ..can sit a long time.

Quiet and comfortable when back packing in.

Cons..

The Bullet is not like the Viper and takes about 5 to 10 minutesto set up..I uusually have mine already set up and locked up..took me about 5 tries to get comfortable packing and unpacking it..but now I can do it blindfolded.

Cost is a little steep..I paid 300.00 for mine.

Summary ...I plan to buy another .There is no price tag for safety and comfort..

Note the olive green metal showing on the picture below..On mine I camo duct taped all of that so when you fold and unfold there are no noises..The rubberized taped muffled out the noises.