I'm guessing I have just been lucky with mine then, had my 50ltr machine for 8 or 9 years now & it's still going Strong. OK it's not run on a daily basis in fact some weeks it doesn't run at all but it has done a lot of work over the years although I haven't used it to spray anything since I got the HVLP machine 6 months ago.
I got it because I needed something portable that I could throw in the car/van & this one fitted the bill but if I was buying a dedicated machine for the workshop I would buy something with a bigger tank.