I wanted to post an update to my design. I really appreciate all the help folks have given me with my design, and all the time they have spent to review my architecture and offer input. Special thanks to Joe and Carl, who sent me tons of info in email and helped me figure all this out.
I contacted EMag and got an answer to my dilemma about where to put the P-mags:
The P-mags should be put on the main bus because we only require a battery for starting. After 800 RPM or so we switch to running off our internal generator and do not require an external source. In the event of an internal generator failure we would switch back to the external power (main bus). Be sure to do the minimum cut-out test to see where the ignitions drop off and note it so in the event of an alternator failure you wont run the risk of the having to low of RPM for our ignitions to continue sparking.
If you do put us on the battery directly you run the chance of leaving us on and draining your battery.
With that advice, I've once again removed the battery bus and put the P-mags back on the main bus.
I also posted my design on Matronics and got some additional feedback, including a few comments from Bob Nuckolls himself.
Joe pointed out that I had the voltage regulator wired incorrectly, and I realized I had switched part numbers from the generic Ford regulator on the Z-13 to the LRC3 on the Z12, but hadn't updated the icon or wiring. Bob Nuckolls also gave me some advice to remove a redundant crowbar on the master switch because it's included in the LR3C.
I've moved the starter switch from a CB to a fuse. I had it on a CB so that I could pull it in the event the starter ever hung up. After considering it anew, I realized I could get the same result by just turning off the master, and I'd be a lot more apt to find the master switch that I use on every flight, than find the starter CB. I also moved the LV Warning line to the fuse block, so now I have 8 CBs total: Main Alt Fld, Aux Alt Fld, L Ign, R Ign, AP Servos, Auto Pilot, Com2, Transponder. (The last two are there so I can reduce the load on my E-Bus if needed during an alternator failure, and I'm still thinking about moving them to a fuse and using a switch instead.)
I also removed the alternator's fuselink between Main Bus 2 and the Alt Fld CB. Having two fuselinks in series, as I did at one point in my design, doesn't give me the protection I thought it would. I now have fuselinks between the Bus 1s and Bus 2s. After some more thought I've moved the CBs to the right side of the instrument panel, which reduced the wire run to about 18" from the fuse blocks of Bus 1 (both Main and Essential), so I've kept the fuselink to protect those two wire runs.
I moved the trim and fuel gauge power to the E-Bus. Someone suggested that the power they consumed was a good trade off for having that information on the E-Bus, and upon further thought I agreed with that suggestion.
I also changed the inline fuse from the SD-8 to the 30A that Bob recommends in his Z-13/8. I'm not sure how I got a different value for that fuse, but someone pointed it out to me.
I removed the current limiter between the battery contactor and Main Bus 1 upon advice that a second current limiter was just introducing additional points of failure without any added protection.
I removed the OV light and will use the G3X annunciator for that function.
I've been reading through the G3X install manual to check for inputs from my electrical architecture to its monitoring devices. I changed the shunt on the SD-8 circuit to the part number called out by that manual.
Right now I still have three advisory lights in my design (battery fault, aux alt warn, and starter engaged). I'm not sure if I'll use all of those or use the G3X annunciator instead.
I think that's a round up of all the changes I've made since the last post on this thread.
I'm sure there will be more changes as I start building the electrical system, but I think this plan is solid enough to start installation.
I saw many builders suggest planning everything out before you start installing a single wire, and I took that advice to heart. I probably spent waaaay more time on this subject than most people do. I'm a slow builder, and I'm okay with that. Although my electrical journey was probably overkill for a lot of people, it's what I needed to get an understanding of the airplane I'm building.
I still have a few decisions to make. Namely, the EarthX battery. I reviewed the RV-8 accident last fall and have been giving that a lot of thought. I haven't made up my mind yet, but I feel comfortable moving forward with that decision still tentative.
Dan and Carl pointed out that I had been fixated on a main alternator failure as the most likely electrical causality, which it is not. Having just completed my PMP certification, I took a page out of my textbook and did a risk analysis of various electrical failures (components, failed connections, shorts of every wire, etc.). It's still a work in progress.
One of the main things I learned is you can't just take good ideas from one design and incorporate them into another design without thoroughly understanding the implications/functions of each component, which I do not. I've read Bob's book more than twice and spent way too many hours working with my plan, and I'm still a novice. Thanks again to everyone who helped further my education.
I'm looking forward to FINALLY installing my first wire!