I'm going to buy a Vacuum pump tomorrow, and I'm kind of confused on which one to buy. I will be working mostly on cell tower sites, with a possibility of a little bit of residential and refrigeration. I went to the supply house and my head started spinning when they were explaining all the differences in the JB line of pumps. Which one should I buy, the Eliminator 3, 4 or 6 cfm? Or should I go with the Platinum series 3, 5 or 7cfm?