Usually a good hot water cleaning and brushing is all you need to do occasionally to get the Wagner hvlp going again----and replacing the air filters. The problem with the Flexio 590 is the same as the hvlp Wagner Control Spray: the filter intake is on the gun itself, closer to the spray area, so the filters clog more easily, and need to be replaced regularly. But at a whopping $1.79 for replacement filters, who can complain? I do like the Flexio 590 claims of having more options/control over the spray and power.
If you're going to stick with Wagner, I'd suggest going with something like the Wagner hvlp Control Spray Plus: http://www.gleempaint.com/wagner-control-spray-plus.html
The air intake and filters can be kept further away from the spray area, and is a bit more powerful as well. It can also use the old control spray parts and attachments. It's hard to ignore the low price point of the Wagner hvlp system. The Flexio 590 would be better if the motor and filters were separate, which also lightens the weight of the gun---nice when doing a lot of canvas.
Otherwise, I'd look at the Fuji Mini Mite 3....