NHibernate is not really a good fit for our environment due to all the dependencies. (Castle, log4net etc.)
Is there a good lightweight alternative?
Support
Here's a big list of alternatives, ones I'd recommend:
Those 4 are the lightest ones. Subsonic, ActiveRecord and others are aimed at large systems. They work fine on smaller systems but (atleast for ActiveRecord) come with a huge list of dependencies and overkill for a small system. I'd go with Lightspeed and say anything under 8 objects is a small system, and simply using NHibernate because it's widely adopted is good for scaling but in the short term makes no sense - and having a layer between the ORM and your consumers can work around that anyway.