How are the spice integrations for kicad now? I haven't used it in probably 10 years so I'm not sure where it's at anymore. I also had trouble using it for laying out traces where length/resistance was critical (high frequency signaling). Altium has been the only thing I've touched recently, but I also rarely do circuit design now, so a "friendly" interface is nice. That's why I prefer using fusion 360 to solidworks or nx.
I don't use it but I have heard both good things and bad things about it. One of the big limitations is the fact they use ngspice for their simulation and many models are encrypted. So lots of folks use it as a frontend for ltspice. TL;DR, it can be challenging, but there is support for it.
