Rotarys are no good for 24/7 usage because of the low back pressures we use in computer phase change, running a rotary in vacuum will knacker it within months.

Recips are a better alternative for 24/7 setup, they are mainly low back pressure, but won't reach the temps a rotary can unless it's a massive and noisy lump.

If it's a now and again benching unit you're after, then go rotary, if it's 24/7, go reciprocating

and no i'm not a phase expert, just read it somewhere :p