Don, about getting stuck hanging on your Blakes...

When you hang in one position for a long time on a Blake's it tends to lock tight on the down rope. I've noticed that Poison Ivy is a little more prone to this than other ropes. To unlock stand on your footloop or footlock the down rope, you want to unload the hitch the same as if you were ascending. While it's unloaded try moving it up. This should be enough to unlock.

Descending fast...
A split tail will theoretically allow you descend faster but you can still burn your main rope doing that, moderation is better. A split tail saves wear on your main rope but it is most useful for passing branches or recrotching, it saves the trouble of untying and retying your Blake's in the tree.

Split tails increase the complexity of your system, you'll have more safety checkpoints for your pre-climb inspection. Split tails also introduce some biner management problems at your saddle delta. Not show stoppers but things to consider.
-moss