I received some new images of the SIONICS Weapon Systems Dissipator barrel (below). This is technically a “mock” Dissipator with a low-profile gas block in the mid-length position which is actually the preferred setup in terms of reliability. In one of the images, you can see that SIONICS secures the handguard cap to the front sight base with a set screw – a step that is necessary due to the lack of gas tube in that position.
Given SIONICS’ track record of quality, I think this barrel probably just vaulted itself to the front of a very short line of available Dissipator options. Fans of this configuration are likely dancing in the streets as I type this.