I only have experience with regular Alpacas, and the only modding I've done is changing the springs.
But they are very smooth out-of-the-box. Noticeably smoother than Cherry MX Red, Gateron Red, even Gateron Yellow.
From videos, I've seen and heard that they sound better after lubing and filming. And I know they have wobble out-of-the-box because I've experienced it.
So there is good evidence that Alpacas, while not perfect in stock form, become very good switches when lubed and filmed. Those two modifications are necessary. Not just lubing them, but also applying a film to stabilize the switch. Those two mods will make them top-rate.
I don't know much about the Silent Alpacas, but I have some on the way. The reviews say that the Silent Alpacas are not that great from the factory, but improve very considerably with lubing and filming, to the point where they may be the best silent linear. Don't use the Silent Alpacas without modding them.