Yes RESTful web services are not that bulky since they have don't have the SOAP wrapper however let us not get caught up in RESTful services are ideal in a SOA enterprise. The problem with REST is that it is designed for point-to-point services with minimal reuse. This is the same type of problem where SOAP based services exposed method calls which required specific datatypes in their Web Services Description Language (WSDL). When it is a point-to-point services, alot of work is spent in formatting, transformation and processing information to fit the specific datatypes in the non-reusable methods. To make a SOAP based web service more SOA friendly, it is recommended that the services take XML documents as the parameters in the web services method calls. This way one XML document can be passed around where the contents of the XML document might be altered by various method calls. It is not practical for RESTful web services to pass a reference to a XML document as a request parameter.
RESTful web services are great with AJAX however I wouldn't recommend using RESTful web services for services which are highly popular, reliable and have a potential to be reused alot.