I see the same behaviour. The Toolkit seems to cache when the cache is disabled. I just don't think it works. However there is a way to empty the cache, stop then start the Toolkit & the cache is empty. Very annoying during development however.
It seems the toolkit has it's own cache that it uses in addition to the device settings.
That is, even when caching is disabled for the device "NMB 3.0.1", files are sometimes supplied from the cache at \Program Files\Nokia\MobileInternet\WapServer\cache.
Can this cache be disabled as well? Is more information available about this behavior? Thanks.