My son and I put them on all our Summits this past year- his Goliath, my Goliath which is used the last 3 weeks of archery and all of gun season, and I have a Bushmaster top section for early archery. I put in over 130 hours in my Summit with the Hazemor seat this archery season, so I feel my evaluation has some merit.
First and foremost, ease of climbing--tremendously easy to climb with this seat versus the traditional seat. Second, weight, I think you reduce the overall weight of the stand by 3-4 pounds, which by the end of the season, that begins to wear on you carrying it in. Third, comfort- you sacrifice a little comfort on your back, but not your butt. The sling/hammock style seat is every bit as comfortable as the regular seat. Fourth, packing the stand is much easier, just make sure the seat doesn't slide too far to the rear before you hook up the platform section.
Fifth- positioning in the stand. For archery, it sits you higher between the arm rests, making sit down shooting easier, and standing easier. This becomes a negative for gun season, I went back to the traditional seat because I like to sit lower and use the front rail as a rest for my elbow to take a shot. I also like the traditional seat for gun season for the added warmth.
Summation--well worth the couple of bucks- no regrets for archery season- will continue to switch back and forth when going from archery to gun season. As I pack my stuff up for the winter and spring, I will be putting my Hazemor back on my Goliath (it never came off my Bushmaster).