G'day Chefrob, I'll go for the second part of your question first in relation to re-attaching the portafilters after each shot. I believe that this is standard practice in the commercial world (it should be anyway) to maintain the temperatures in the pf's. Thermal stability throughout the machine, including the pf's, is a necessity. The second part, about leaving the machine on 24/7. This has been, and probably will be, debated ad-infinitum. There are pro's and con's for each scenario, ie turning it off when not in use, or leaving it on 24/7. Some components in the machine respond well to being at a constant heat (being left on all the time) and this will extend their lifespan. Some components, on the other hand, will have a shortened life span by being left on all the time. I don't think the power consumption would vary greatly between being left on 24/7 and being turned off at night. The power required to get the machine up to temp in the morning would be quite high, with the elements switched on for longer periods to heat the boiler up. I think a bigger risk than electrical problems would be water connection failures. If a water pipe or connector fails in the middle of the night, the damage this water could do would be huge (depending on the surrounding area of course.) Hope this helps.