Again... even if we a assume a safer-functioning, compact "emergency" type of warp core, you still have to carry tanks of reactants one of which is antimatter. You don't just have to worry about that antimatter contacting the stored matter reactant, because EVERYTHING on the ship is matter. Lose one iota of containment on the antimatter tank and you've got big boom-boom. Storing antimatter in the engineering section is a necessary evil; storing a secondary amount in the part that's supposed to be a last-resort safety
option is irresponsible as well as defeating the point.
Further, as I'll say again, it's not just the extra core (compact as you can imagine one.) It's the reactant storage I mentioned, it's control equipment, it's monitoring stations, etc., etc. There's a reason that the engineering section is as much larger than just the reaction chamber as it is. Everything you take out to make room for the emergency core and ancillary equipment is lessening the ability of the ship to perform in some way, great or small.
Mark wrote:Without a warp drive it turns into a single, very large lifeboat.
So? That's what it's there for. Increasing it's abilities beyond its intended function is great... except when, as I've shown, such an increase both compromises the ship's abilities to perform its functions AND radically endangers the very people it's supposed to help.