So I've actually done both methods of powering things, but I've pretty much refused to do the resistor/relay due to safety concerns. I don't like having a part that's sitting there always on emitting heat, and if fails causes a fire. Resistors have a tendency to go up in flames.. not a risk I wanted to take.
The penthouse itself is fine if you have amps that don't have a lot of internal capacitance, like my Helix V Eight was fine. The M one, was not.
I've run everything off the 12V battery under the hood now for months with absolutely zero issues. I personally think its a good solution. In fact, my next goal is honestly to move the amps to the frunk. There's a lot of advantages to that.. shorter wires for everything!