An associate of mine has found a report discussing a new military-issue plate known as the LSAPI. From what I've gathered, and I could be wrong, the LSAPI is a companion plate of sorts to the newest-generation XSAPI that theoretically mimics the 2006-present relation between the SAPI and the ESAPI. This LSAPI began development, according to the report, around 2012-2014 and I have little-to-no information on it besides the above. All I know is that the XSAPI predates it by a few years. I find this interesting since I previously believed the XSAPI, as a heavier plate relative to the ESAPI, existed purely to fill the role of a high-end contingency plate for the sudden emergence of threats like 7N13 / 7N26 / 7N37 / 7N39 while the ESAPI continued its reign as the general-issue hard armor insert. Now, if the LSAPI's apparent state of companionship is any indication it seems that the XSAPI is set to fully replace the ESAPI while the LSAPI, which seems to have similar protective qualities to the ESAPI but is expressly described as lighter, is the replacement for the original SAPI. Here's the report:
I suspect that the greater role of the XSAPI, as a very highly-rated plate only surpassed by ATT's Model 4520 and a few others, will have substantial implications for the CONUS body armor situation due to potential reductions in the cost of Silicon Carbide relative to the vendor-favorite Aluminum Oxide used by most hard armor inserts.