Really? Well, I was thinking of having the room like 16 radius; maybe strategicly placed columns can break up the "straight line" effect you speak of -although I haven't seen that happen alot before for more han 3-4 tiles anyways. Also, I'm utilizing the ABSENCE of water as the trigger, so it might behave differently.
If need be, I can further increase uncertainty be using a specialized pump stack I designed months ago but scrapped because I couldn't find a feasible way of feeding it data that would be consistantly meaningful. It works like this:
A bunch of 1x1 reservoirs (with pressure plates) are layed out in three dimensions, with pumps linking them. All the data, therefore, is preserved in discrete quanta, besides for the occasional irregularity that only increases randomness. Multiple pumps are hooked into each one of at least a dozen imput signals, which my new randomizer can provide. Only the bottom layer has inf water, the rest must take the "ON" signal from a device on the floor beneath it. Thus while multiple pumps are activated with each input, it is random which output signals actually work. The higher floors would be on less often, and there needs to be a regulatory system (like having a hatch that needs a seperate signal from the pump) if they aren't to merely "Pulse" on rare occasion. Although, the problem might solve itself as the lower levels get increasingly filled; I haven't tested it.
A third circut could be added to solve the "Pulsing" problem: a long series of these "descrete" memory gates that connect and empty directly into an infinite water source. Machine logic works really well for OR and AND, so the imputs from the last device could be connected to, say, a 3x3 grid of gears to activate/deactivate each one. The output of that circut would hook directly into the features that are to change -The Cube is now possible to construct. I think I might start a thread for that...