The Stein Skywalker pulley is not a Hitch Climber in disguise with a limit of two attachment points (instead of three) - contrary to comments made on some tree climbing forums late last year.
Size is one factor: the Stein Skywalker is quite a bit smaller than the Hitch Climber and the sheave is designed to accommodate ropes up to 13mm as opposed
to 14mm on the Hitch Climber. And its hitch tending fairlead ability is possibly not as refined as that of the Hitch Climber.
DMM Pinto, Petzl Fixe or ISC Fixed Micro for single attachment, Stein Skywalker or CMI Mickey Mouse (currently not sold by Treetools) for two-hole attachment and DMM Hitch Climber for three-hole attachment. (Well, in the case of the Pinto single attachment is not entirely true, there are two attachment points on the Pinto - the top holes and the bottom becket - but that is somewhat unique).
The DMM pulleys are possibly better suited to the management of friction hitches due to their 'rounded' construction and attention to 'fair leading' in the side plate design. But that does not limit the other small pulleys on the market.
If you only need two holes for attachment in your hitch tending system then consider the Stein Skywalker. It can also be used in rigging where two independent tie points are required (similar to the CMI RP141) or in a floating double D configuration on your bridge.
Whatever configuration you conceive, the Skywalker, like the Hitch Climber is better suited to oval shaped carabiners for attachment.
The Skywalker pulley is made under license by ISC in Wales but designed and branded by Stein.
The CMI 'Mickey Mouse' and the new Stein Skywalker side-by-side