Climbers are beginning to see the energy-efficient benefits in SRT access and more and more variations of the 'tree frog' system are presenting themselves on YouTube.
Have a look at this 'sit-stand-sit' tree frog configuration from Tanglewr.Jerry Lynch will be a bit miffed because Tanglewr uses a derivative of his Earth Stick concept (released at the 2011 Southern Arbor Day Arborcamp) forkeeping the access line under tension until the weight of the rope comes into effect.
Another innovation is the use of the Blakes hitch to help release the cam on the chest ascender (when it comes time to descend).