How thick is the satin sheet with respect to the smooth PEI sheet and the textured sheet?  

Tada

The thickness is not the issue. As pinda check the height from plate. Problem is the texture, that can make the sensor think, it is higher as it really is, on small peaks of the texture. Otherwise you will not get the perfect squish on the sheet on first layer.

And overall, I do not think, there would be an issue, even when the high would be like 2mm, Pinda doesn't care about that. I think that the sheets are in core same, just the thing on them differ. So textured sheet should be the thickest of all.

Thickness of Prusa sheets

To answer the question (measured with digital caliper):
Both (satin and textured) sheets have same thickness of about 0.65mm. Standard PEI (smooth) sheet is about 1.3mm thick. Because of nature of measuring with digital caliper, take these values as +/- 0.05mm.

Z value for satin sheet

Thanks. For my printer, I have a working Z value for the textured sheet and the one for the smooth PEI sheet. When I first use the satin sheet, I have to start somewhere especially not too low to scratch it. So if the satin sheet has the same thickness as the texture sheet, I just start with the Z value for textured sheet and go from there? 

I think, thickness of sheet should be taken as "good to have" information -so we have basic idea about what negative Z-offset to expect at first layer calibration. But there's always fine tuning which depends on actual sheet surface.
In this case we know, that for satin and textured sheet, Z-offset will be about 0.5mm lower than for smooth sheet. But that doesn't mean satin and textured will have the same Z-offset. Imagine sheet surface as profile on car tyre, where satin sheet can be compared to (slick) summer profile and textured to winter tyre profile. That is, textured sheet relies on "grip", which means filament should be a bit "squished" into surface (profile), to have good layer adhesion. And so, even textured sheet looks kinda rough, it will have lower Z-offset than satin sheet. But then, it also depends on filament type and temperatures.