05_sprcrw just about nailed it....
-in my opinion this are very comfortable, like sitting in a hammock all day.
-and i agree that they are pricey but well worth it, lets see tree saddle $230
-climber is 300 comes with cheap harness, so a good harness is around 150, so 450 if you go with a climber, but a climber cant do half the thing that a saddle can.
-as for steady shooting with alittle practice you can be just as steady in it as you are in a climber.
-i too put both knees against the tree and is very solid. they even sell pads but i havent needed them yet.
- and they are made to with stand the same weights that any climber can hold.