This has been discussed many times, before, and IIRC the conclusion was that 1Ks and UGSs can use the First Class line, with the presentation of your elite card. I've found that the checkers, now, can just read it off BP. My last flight, out of LAS, the CSR reminded me that 1Ks and UGS can now use the First Class line. I have no doubt they have let 1Ps and 2Ps through, but I doubt that it was the result of official policy, but rather a lack of knowledge or care, on the part of the checkers.