If you think the S12II is worse than the CXM you literally have no idea what you're talking about
So the majority of power supply experts have no idea what they are talking about because they aren’t a Seasonic fan boy?
The PSUs are 8+ years old, using a group regulated design. This means performance is average and out of spec voltages in Crossload, which is what modern computers use. The CXM uses a much newer, DC-DC design offering overall better performance, and way better performance in Crossload.
The S12ii uses horrible protection IC so it is missing crucial protection like OTP and OCP which the CXM has.
The S12ii is rather loud under load. At a 250w load, fan is at 1770 RPM as opposed to the CXMs ~1200RPM.
No reason to consider the S12ii nowadays, when a CXM grey label, Corsair CX 2017, MasterWatt, Pure power 10, etc can be found at a similar price.
https://ru.gecid.com/power/seasonic_s12ii-520_bronze_ss-520gb_2015/?s=all