Any disadvantages to running a vaccuum pump? (for oil)

My builder has sworn by his, he's ran it 5 seasons if I recall & like I mentioned swears by it, in the catch fuel has a chance to flash off, no moisture allowed to set in, like if you have L19 arp rod bolts which will immediately start rusting. I haven't yet spoke about the too much vacuum side but I've seen his engine, watched it run down the track & trust his opinion. Nice motor, is that plate A.R.E. ?
Yes A.R.E. slightly modified and anodized.