Yes they are considerably more reliable in my experience.
My Chargemaster scale drift quite frequently, and accuracy is 0.1-0.2 grains, along with it's slow response time and tendency to overthrow it is far from perfect.
First off the normal budget type scale is of a strain gauge type, vs magnetic force restoration so it's different technology in them and the weigh cells are a lot more accurate and responsive.
Strain gauge balances have a tendency to drift in general, and the software is often counter productive as it's built to restrict drifting.
Look at the linked youtube videos for a a good and visual explanation, from someone that makes a living by selling them.
A strain gauge scale really can't measure reliably trickling powder kernels no matter what accuracy it has given.
The more expensive scales are built from higher quality components, and some have filters and RF shielding.
The draft shields helps eliminating airflow that can affect the balance.
Temperature will still affect them all though, so it's not wise to move them from a cold storage to a warm room and use it.
As for calibration it should be still be done at least when you start, and i like to do another check shortly after.
Never experienced drifting or having to rezero during load work with my Sartorius.
It also give me instant accurate reading of dropping one kernel at a time.
Digital Scales: GemPro 500, AY123, Sartorius GD503 within AccurateShooter.com
Strain gauge loadcell vs electromagnetic force restoration - YouTube
http://www.youtube.com/watch?v=89BOlViQXto