I like ei and am a fabricator by heart , so built my own. I believe the sds is a far superior product and very reliable. The cpi 2 has built in batt management, so just as elec fault tolerant as pmag. Price is substantially less and really substantially less when you consider the new $1000 every time you send it in policy. While carls seems to work forever, it seems that is quite far from universal. NO ONE sends in there sds system; it just works. The ability to add a LOP switch is invaluable imo. I have that on mine. Dead simple and can even build the tables so that if you forget, it will still retard timing at high power.
If a user can’t deal with the more challenging installation requirements of sds, I would recommend a surefly. So far seems much more reliable than pmags.
I understand you doylike the sds site, but you can just pick up the phone and call them. They will explain everything for you and help you make decision.
I still have a mag on my 6. Nothing wrong with that. I still get variable timing from my ei, with no need to deal with elec fault tolerance.