I like how more toolbar space is gained by decreasing gaps between toolbar buttons etc while Office-style toolbars is turned on. I don't like the menus of the Office-style. Is there a way to get the same spacing in toolbars without turning on Office-style toolbars? If not maybe it could be added in. 
Spacing can be adjusted in Preferences / Toolbars / Appearance.
Right, that helps but why doesn't the setting you mention also adjust the location bar toolbars set in Preferences / Location Bar / Toolbars ?
Mainly I would like no gaps horizontally around the location bar path field combobox. With Office-style toolbars there is no gap.
(Images have been enlarged)
Office-style: on
Office-style: off
The toolbars in the File Display Border overrides the normal spacing, although the intention was to give them smaller spacing.
Maybe we should change it to use the global spacing setting when it's even smaller than what it normally uses. That would make sense, I think (at least without looking at the code yet).
I think there will still be a small amount of extra padding when using the normal style, due to how Windows themes (visual styles) are laid out. (You can see the difference by placing the Location field on a normal toolbar, with nothing else on the same row to make it taller, and then toggling the Office style.) But it'll be less of a difference than it is now when using really small spacings.
If doing so would allow for no gaps as explained above with office-style off, that would be greatly appreciated!
I know I sound like I'm being extremely picky but coming from the days when DOpus didn't have the location bar and just the static header I was accustomed to a thin static header (taking of course into account font size used). When I finally changed over to using location bar I lost some horizontal space. I barely ever maximize my lister window and it usually occupies about a 1/4 of my monitor 90% of the time. This is one reason I would like no gaps.
Edit:
Also I am in list view a lot of the time, so I can see more items at once. The file display when items reach the bottom of the lister are almost perfectly at the bottom of window. So depending how many items and therefore columns wrapping around in the list view, those extra 2 pixels from location bar shift the last item in the lister down 5 more item spaces. If for example there is 5 columns in list view.
Example:
This doesn't seem to have changed anything on my end. Appears exactly the same comparing 13.24.1 to 13.23 while adjusting button spacing to low values.
It should make a difference when the spacing is set to 0. (When it's 1 or higher, the old spacing for the FDB toolbars would be the same or smaller already.)
Vertical spacing 1 and 0 are the same on my PC.
From checking again, it only makes a difference with high DPI. At standard DPI, both 1 and 0 vertical padding already make the location bar as small as it can be (without reducing the font size).
Then how is it doing 0 spacing while Office-style toolbars is enabled? Aren't you controlling the spacing in code while Office-style toolbars is enabled and therefore can do then same when it's not? Or maybe there is a setting builtin for the toolbar offered by windows to enable office style and it's done behind the scenes by windows?