I've seen mixed reviews on YouTube. Gushing reviews from retailers, mainly about the finish,, but some independent reviews have rubbished the pickups. Odd given, apparently, the same pickups are used in the SG versions.
P90 fitted SGs are just about unobtainable at the moment, and P90 Casinos (yes, I know, solid vs hollow, completely different animals) are scarce too. A P90 loaded (semi)hollow would scratch two itches at the same time though.
I've been "whelmed" [not overwhelemed, not underwelded, just whelmed) by the P-Rails I fitted to my Gibson SG.
Buying a $500 to $700 guitar then spending another $200 on SD P90 pickups isn't viable financially at the moment either. Not withstanding the likely my wife / a bread knife / my manly parts incident that might ensue...