I would prefer it be a control computer that creates a group that falls "outside" the standard ship limits, so that it becomes a solid, non-moving part of the ship (in other words, part of the ship's own block grid, instead of a rail-attached separate entity grid.) The reactor blocks that are linked to that control computer can add up to 1.6 M maximum energy (This limit is entirely arbitrary, can be different in the game, and should be server-configurable) for that computer, which in turn adds that energy level to the ship's basic energy levels, as if the group were a docked reactor.
Expand the idea by allowing shield sharing or any other block (E.g. Cloaking blocks, jump drive blocks, shield blocks, weapon blocks, anything.)
The nerf? Make that computer control block target-able individually as a "subsystem". And if that control block is destroyed, all linked system blocks are inactive and don't add to the ship at all.
There are many ways control computers could be "abused" by builders, including adding a bunch of computers and mis-labeled computers (I think they should be label-able, like transporters) to confuse enemies.
Basically, "Control" computers would be a way to have docked reactors without all the game-hobbling lag.