EDGE 1040/1050 - VCENTER

Looks to me vcenter is working correctly, but the fonts on the 1050 have different space at the bottom and the top.  Here's one of my test apps in the sim for the 1050

And the same app with the 1030 (white space looks more equal).  On the 1050, the "L" is pushed right to the top, while it's not on the 1030

You might try using getFontAscent/getFontDescent to make it look better

Here is another view with descenders.... Interesting. So for the older devices, it centered from the baseline to the top. For the new devices it centers from the bottom of the descenders to the top. So you really need to check if you have descenders and check which device is being used... if for example, you need to vcenter text. In my case, I want to vcenter numbers with no descenders, so on an EDGE 1030 and earlier it works. On a 1040/1050 I need to skew it down by half the descender height.

You must not have many watches as target devices.  With 100+ watches released over the last 9 years, running into stuff like this isn't uncommon.  Fonts can really vary on them.

When adding a new target, handling font differences can be the biggest challenge.  I know a couple people that use custom fonts, even in things like data fields, just to avoid the hassle

Even then if the simulator doesn't behave like the real device, it won't help for most developers, as we can't afford to buy all new devices...

That's where having a user send a picture can really help for a device you don't have.  I've even done versions of apps with a tiny amount of debug info on the screen so the user can take another picture with the debug info.  That's easier than having them create a log file and sending me that.

That's true, but even though I know there are few pixel mismatches in the positions of the DF labels in many devices I never had any user contact me about it (out of 190k downloads and every device above CIQ 1.2.0)
On the other hand last week I did report such things with screenshots to another developer who already fixed it. So maybe it's just the number of pixel perfect users out of the full user base or luck or I don't know what...

But tell me one thing: wouldn't it be better if we could trust the simulator? Exactly for these types of things it could/should be a perfect tool.

As Kyle is known to say "It's a simulator and not an emulator".

There are a whole bunch of things that in the sim don't work exactly like on a real device.  And if the platform groups do something like make a small change to a font, it might not show in the sim until the next SDK release.