The way I'm looking at it is the WP40 costs about 1/5 that of a MP40, so even if the WP40 breaks after a year or so, you are still money ahead for at least 5 years, provided that if/when it breaks it doesn't leak electricity into your tank, which admittedly is a concern. Apart from that, there are loads of threads on the MP40's wearing out after a year or two and require replacement of certain parts (e.g. the bearings or even the whole dry side), so you have to pay to replace those periodically as well, which is really just kind of ridiculous IMO for a $465 piece of equipment. If the MP40's were quiet and were really a bullet proof piece of equipment that would last forever, I'd probably just pony up the cash and be done with it, but the fact of the matter is they aren't. They're awesome, but at this point idk if they are $465 awesome.