I like the idea of making all 4 power levels equally important and right now there just aren't many situations where auxiliary power is seriously considered. I thought I'd heard that Auxiliary was at one point or another involved in crew and hull regeneration but I either made that up or it has no significant effect. I think the resist rate is a good idea and increases the importance of power management.
Why pump excess power into a disabled system? Redirecting it to the other 3 makes sense to me. Of course, I don't really agree with a 25% minimum to all systems either. I wonder what it would it do to the game if people could sit with Weapons and Shields at 100% but with Engines and Auxiliary at 0% or 5%?