From what I understand, the 155 plt is being used for the experiment but in eventual execution the EFSS can be used as well. It won't be attached, it will be in direct support. As it is now, a battery is assigned as direct support to a battalion. During ECO, two guns (or tubes) will be DS'd out to each company. An 0802 will be in charge of each platoon as a platoon commander/FDO/XO all in one and will clear fires (allegedly anyway, grunts have this ridiculous idea in their head that they're better qualified to clear fires than an artilleryman). Depending on the environment, each platoon will require security if not co-located on a FOB. The logistics and security issues are being tossed around by MCCDC as we speak.