Fast minecraft two-way piston elevator / escalator - moves items, players, mobs

This is a relatively fast piston elevator/escalator/dumbwaiter that can move items, players, mobs, and materials (blocks) in both directions. Benefits include functionality in Minecraft 1.0 with no reliance on clipping or other bugs, no elevator cars (it's more like an escalator, where multiple objects can be sent up or down, [but not both] simultaneously without waiting for the first to complete), as well as a modular construction (the structure repeats every four vertical blocks).
If enough desire is indicated, I will upload and post the link to an MCedit schematic, although construction is simple, consisting of a central shaft surrounded by two spirals (one for the lifting circuit, and one for the downward circuit). No pulse limiters are needed, since everything fires in sequence. Repeaters are needed to maintain the pulse, and slow it down until the items/players/mobs/goods have risen (or fallen) into place. The overall timing might likely be improved to function even more quickly, as this was my first attempt at a bidirectional dumbwaiter. The footprint might also be made smaller - I'm not a redstone wiring genius, by any means.
Any yes, I know I could put a single pulse limiter at both the top and bottom to allow even more simultaneous loads of objects to be sent up or down, but I simply just haven't gotten around to it yet (and I'm really not proud of the hookups at the top and bottom - someone with a lot more redstone finesse should really redo them...)
I was inspired to build this by the minecraft wiki entries that mentioned a similar piston mechanism to illustrate a one-way elevator/escalator, but then went on to seemingly suggest that two-way elevators are of an almost completely different (and slightly slower) design. I just wanted to show that a two-way elevator was possible based upon the original one-way design.