OK so here are the beavertail and undercut comparisons.
The 91197 has a slightly different beavertail than the others.
The 99021 and 99041 are certainly more upswept than the P01 but are slightly different than the 91197. They seem thicker.
The SP01 does look to have a very similar beavertail than the 91197.
When I compared undercuts, all the steel framed compacts appeared the same as the SP01.
91197 vs 99021
91197 vs 99021
91197 vs SP01
91197 undercut
99021 undercut
99041 undercut
SP01 undercut
3 unicorn beavertail shot from the bottom