All the major brand membranes last3-5 years depending on your water quality to start. AWI sells membranes and I bet there the same quality your water company uses. If it works for you then the water company is the way to go. But don't fall for that line that we have a far better product then any online store can get you.
Did he tell you that if your water pressure is low that will effect the water output and the length your membrane lasts?
And at $300+ I can get a unit from ebay and have money left over to buy replacement filters, membrane and a fish or 2. JMO
.. Sounds like the Water company should open a LFS
Down side I had to heek ot up myself... which was not a mahor project .. Hope it woeks out for you.. Post some picks when there done..