Ron, first of all great post, secondly, maybe not the most accurate tittle, more than loading workflows definitions form the DB (.xaml file content) or any other way that it can be turned into some string value using the DynamicActivity method i.e:
var activity = ActivityXamlServices.Load(new StringReade(wokflowToExecute)) as DynamicActivity;
This is an elegant workaround to implement service partitioning on WF, back in the
beta I asked something like that http://social.msdn.microsoft.com/Forums/en/wfprerelease/thread/41ecf7c5-8c74-4ec9-9bdf-437015b17ceb
The "limitation" of one WorkflowServiceHost per WF service is one of the reasons I decided to no
use WF services on one of our company's main solutions, given the number of services to implement, using WCF routing wouldn't be as practical or maybe not a clean, and using pick activities would be irrational, so we used plain WCF instead.
Currently we have another interesting scenario and the approach you're following gives me another option on how to handle this situation, so, thanks Ron and keep up the good stuff coming.