We've gone ahead and made the dojo.transport bind argument off by default. You can turn it on for bind calls individually like so:

dojo.io.bind({
  sendTransport: true,
  url: '...', // etc...
});

Or globally via djConfig:

djConfig.ioSendTransport = true;

With regard to FormBind, you'd specify that one of two ways:

// at declaration
new dojo.io.FormBind({
  formNode: 'myForm',
  sendTransport: true
});

// later on
x = new dojo.io.FormBind({...});
x.bindArgs.sendTransport = true;

This has been a public service announcement.