Sorry for the off-topic question, but thanks for your prompt answer. I get it now... So if everyone is working on the same block at any given time, would'nt it be better to have a more powerful pps machine than a bunch of smaller instances?
No. The probability of hitting a block is proportional to pps. Your net pps at constant diff over a long time should give you the same no of blocks no matter whether they are on a single or multiple source.