Hi there, not sure about different brands and reliability, but the main diference between 19 and 17 is the barrel (inner & outer) length, slide length (hence the difference between front and rear sight, in which affects your aim ability if u uses ur sights to aim).
On the frame side, 17 is also slightly longer than 19. Grip angle is slightly different due to the backstrap 'hump' length. Also the finger indentation on the 17 is slightly spaced out more compared to 19s.
And since the barrel and slide difference, I believe the weight distribution is different as well. I have not tried both 19 & 17 to note the actual weight difference, not airsoft version anyway.
Hope this helps.