No point in bothering with blast relays etc, with low current motors like the 25K motors you are running.How fast does a motor have to be for the power loss to make a difference? My fastest motor is a 25K. I can't tell a difference in acceleration or top speed, but that doesn't mean that there isn't a difference. And maybe even if there IS a difference, the control of the SCP (which I really like) may more than make up for it.
I have a good analog controller. I got the SCP so I could try out digital with a trigger controller. I'm finding that I like using it for analog, too. I strongly suspect that the condition of the braids on my cars makes more of a difference than the slight power loss from the controllers MOSFETs, but I don't know that. That's why I asked.
As I'm sure you know even low currents passing through low resistances will produce a tiny voltage drop. With low current motors the drop is too tiny to be worth bothering about.
You are absolutely right about the importance of a controller that feels just right to you.
You are also absolutely right about the importance of having the braids working properly. ( I might add getting tyres, gear mesh and bearings properly set up)
I reckon you'd be well advised to stick with the controller you like and if that last little bit of performance matters to you spend time tweaking the car.