I've added Pier-Setup to the pier2 repository, allowing me to commit a change to the package which fixes the bug Reza reported below:
 
An open (Seaside 3.0 ??) issue:
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 When hot switching distributions via the Design Chooser interface in the Home page, the following call sequences raises an exception:

WAApplication (WARegistry) >> urlFor:ifAbsent:
WAApplication (WARequestHandler) >> url
WADispatcher >> urlFor:
WADispatcher >> nameOfHandler:

However, by forcing the navigator to point to http://localhost:8080/pier, the new distribution is launched and seems fully operational. 

Cheers,
Reza

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