I'd like to propose a few suggestions to the way size column is shown in terms of number and label formats.
I understand that some of these might be too much customization for a single column and maybe belong better to a custom script (and if you know good examples, feel free to post them here as I've so far only found these one and two that deal with size)
But maybe some you'll find useful for the main Opus options as well. Also, a lot of the ground is already covered in the current auto-size column, so it might be easier to expose options there than to get a new script from scratch.
While I do have size bars displayed in the column background (extremely useful feature, thank you!) that helps read some of the information the following suggestions try to make to bring forward, if there is a big folder in the mix, the bars for smaller files are invisible.
[ul]
[li] First, it'd be great to allow customization of decimal places rules. It's already a great start that you have different rules depending on the number size (1 decimal for single digits, 2 decimals for double digit numbers, 0 for none). So simply exposing these constants as a setting would be very nice.
For example, I'd like to have 2 decimal places only for gigabytes, everything else should have no decimal places (except maybe 1 decimal point for low value (1-9) megabytes). This way 1.73KB won't be taking as much size on screen as 107 KB.[/li]
[li] Change all labels to single-letter (G, M, K, b) as the extra B doesn't convey any information (you already know it's a size column so it's about types of bytes) . This also deals with bytes taking way too much space for their lowly status 
— this can be further signified with a lowercase letter[/li]
[li] Allow font customization for labels, e.g.
123 G (bold black gigabytes)
123 M (normal black megabytes)
123 K (light gray kilobytes)
123 b (even lighter gray byes)[/li]
[li] Allow to change font for size columns to a monospaced one, so that K and M would take as much space and not break number alignment
aligned monospace
K 10
M 10misaligned proportional
K 10
M 10
[/li]
[li] Align numbers by decimal point so that bigger numbers are always more to the left vs smaller ones (an extra space saved by cutting off B from MB put to a good use here 
)
17 K
1.7K[/li][/ul]