Here again the facts of the Catalyst / Pixelmad setup for Live Earth Hamburg in more details:

Server 2 running the "HiRes" LED strip in the backwall.

Strip consisted of Unitek V9 LED panels - total pixel size 1535 x 96 px
Output was two mixes on one screen one left half und below the right half of the strip. Converted to SDI by an ImagePro.

Server 1 running Pixelmad:

Pixelmix 1 : 3 Universes with 400 Pulsar Chromapanels
Videolayers 1-4 Routed to this mix

Pixelmix 2 : 26 Universes with some 220 ELP60 / ELP30 LED striplites (Each 60/30 channels of DMX)
Videolayers 5-6 Routed to this mix

Hardware Setup of both servers was MacPro Quadcore 3GHz with 3 GB RAM and a fast SCSI content disk.
Artnet was run via fibre optic link to dimmercity and was output to dmx by 4 ELC DMXlan node8.

One problem that we saw was that after quick image changes followed by a static images some old data kept stuck in the buffers of the output nodes...