I had a Gilmour 390 and struggled with it for a good year.  It sucked.  But it sucked because often it didn't suck.  Crappola, and all though the 390 is cheap, it is not worth the trouble.  Now, the 362. I could not stand the thought of buying another hose end sprayer from Gilmour after my experience with the 390, but I will say the 362 has worked perfectly.  I really have no way to check if the concentrated mixing is properly calibrated, but it seems okay.  If I had to guess, I may lean towards it being a little stronger than the setting.  Just speculation.