We are not interested in supporting various proprietary plug-in formats since this usually increases problem base more than gives off benefit. Beside that, VST specification which is supported by SawStudio is very "direct": the CPU overhead added by it is very small.
This is a known problem, but unfortunately we can do nothing to resolve it: our plug-ins conform to VST specification and are able both to load and store preset information (they are working correctly in a vast majority of VST audio host applications). We think that SawStudio is fully responsible for such erroneous behavior. To our knowledge, this problem was already reported to SawStudio developers, so it may be fixed in the future. But you may contact SawStudio developers to try to make this happen faster.