Eeek 40 micron rated vacuum pump for that price?! I will skip out I have been eyeing yellow jacket one for some time. It feels much heavier probably meaning less noisey. I am not sure if I like my robinair too much to be honest. I usually do last evac with a lab-grade maximus vacuum pump 2cfm (yes 2cfm) rated converted for HVAC use. Funny thing is, I consistantly get faster and better vacuum from this... 70-80lbs monster 1/3hp 2 stage vacuum pump than from 30-40lbs robinarie 2 stage 6cfm... (faster pull down, down to where I deem finally evac'd). It was "old clunker" I picked up from a buddy when I started and funny enough, it's still the best vac pump I've seen. I search on e-bay for decent one like that to be converted but even for old used equipment, price isn't cheap. (leybod is another term to search for this... you need to convert it to have MPT fitting etc quite often though).
This pump is about 2-3 times quieter than the robinair and just better since I don't have to carry it to somewhere.... (typically... that is).