OK. Sorry guys, but previous problem with PRParagraphs wasn't so simple as I thought. But it's ok now. It works, both pier and creole syntax switches can be used right now in PRMyMultiPage-s. I've integrated switching mechanism deeper than in previous version. Now it works on the PR*Parser->parseText level and doesn't make any PRParagraphs at every syntax switch. Also I've removed PreParser and its structure at all... I believe that this will not be needed anymore. Theoretically there is better performance for now (better than with PreParser at least). Also there is a simple/dummy visiting modification to view/edit modified Document structure with new PR*Syntax structures. It needs to be modified in future. On this week I'm planning to implement Creole syntax.
If you want you can test my multi page at http://kamikaze.seasidehosting.st/ (services->Multi-Syntax testing)