[Suicide Junkie]

For P&N, I've made the Quantum reactor about the same strength as that, except mine is 500kt, and stores 1/2 million supplies.
It ends up being balanced with the other supply storage technologies (3x more, 3x more expensive per storage point)

For mines, you can reduce or eliminate sweeping technology to avoid the "nothing" side. The "all" side is pretty unavoidable in a literal sense, but what you can do is force players to spread their mines over multiple sectors. If your minefield is spread out, then not all of them will detonate.
A low limit on the number of mines per sector will help that, but then you have to reduce sweeping even more.

I have decided on No Sweeping, weaker mine warheads, and overall less damage per sector possible from mines.
That way, entering a minefield with a large fleet means you WILL get hurt, but it is unlikely that you will lose any ships. Small fleets or solo ships will still get vaporized, but that's unavoidable in SE4.