I was looking for some trimcaps and found these on Digikey which have a "Top Adjust" and a "Bottom Adjust" version. Here's an image from the datasheet:
Besides mechanical access, is there a reason you would prefer one over the other?
For example, for "bottom adjust", is there an advantage to adjusting these through a hole in the groundplane? I mean, either way, they should be tuned with something non-metalic, so does it matter?
