OK, an update. My Atlas probe is still running strong but the cheapo one has given up the ghost. It now reads too low with too low a slope for me to want to use it any more. It lasted about 2 1/2 years of what I would call good use. This is well over half of the claimed life of the Atlas probe at around 1/4 the price.
Can I just make a distinction between 'a cheapo meter' and 'a cheapo probe' at this point?
A cheapo meter will have very very cheap, possibly badly designed, electronics reading the also very very cheap probe. It will not calibrate well, or for long, it will not be stable.
If you buy in a reasonable PH circuit to read your cheapo probe, or make one yourself, it is very likely to be much higher quality than the circuit in the cheapo meter. The circuit is where a lot of noise and inaccuracy enters the signal, not the probe. If you get a good probe and a cheap probe and connect them to the same circuit you will see this yourself.
The cheap probe will have less reference solution inside and it will not be as well sealed though so it will not have as long a service life and will need calibrating a little more often, but nowhere near as often as the cheapo meter.
Basically, with a cheapo meter, you will be lucky to get an accurate reading at all. With a cheapo probe and a reasonable circuit, you will get accurate readings but you will need to maintain (calibrate) it a little more often than an expensive probe and it will have a shorter operating life.