I've looked into PC'ing the sub but the trade-off doesn't engender (is that the right word?) itself to me, I don't like the idea of sterilizing the sub and killing off the beneficials. I may be misunderstanding what you're are doing so correct me if so. With my method I'm getting colonization within 24hrs and 4 days later the surface is totally covered with mycelia.
Last year I struggled to get anything from the tubs besides trich. Two things really turned the tide, cleaning the manure of sticks and stones and other crapola and dialing back the spawn to sub ratio. I had been doing 1:3 but now settled on 1:2. There is an unknown aspect to this, I had a conversation with another member last fall, he said he'd stopped trying to grow during the summer when the AC is running. His thinking is that the AC stirs up contaminates that the heating cycle doesn't. He got positive results and so have I. There is another change I made to the grow room, I put in a high efficiency air cleaner and was running it for a month before starting the latest grows.
Then there are two other changes I've made with the grain colonization, one grow was done with A2G transfer and the other was done with LC2G. I'm so impressed with the speed of LC that I've made LC from at least 6 varieties of shrooms starting with agar sampling of each looking for good rhyzomorphic growth before inoculating the solution.