Could you perhaps give us an idea of what any of your current 'slope' dimension examples look like, in either 2D or 3D,and how you might WANT them to look, in 3D?
A couple of possibilities are these, for a simple easily visible angle, based on a minor tweak of the geometry of Angular Dimension 2:.
But how would you want to deal with a slope dimension placed (for example) in the middle of a roof face? Something like this?
I've done a bit more googling on how they are represented. I understand in 2D drafting, the common (US anyway) ratio is to a base of 12, as you suggested. and drawn a little off the face or rafter with a triangle of fixed shape (15°) and a number and tolerance beside it.
That would be very different from the basis of Angular Dimension 2, and hard to implement in SU. You could maybe use Steve's (@slbaumgartner) original Angular Dimension plugin, which shows the angle in degrees in a SU Leader Text box, and overtype the angle with a calculated slope.
Can you have fractions? You suggest ¼:12. Wouldn't that be better as 1:48? Or is that not the convention?
How would you want to show a slope for an angle that hasn't got integer rise and run? You probably know (as I half remembered, and then checked) that you can input an angle AS a slope - 1:6, 5:12 for example - to the Protractor or Rotate tools when you create a roof slope, and that could be shown as an exact ratio, either to base :12, or simplified from (for example) 6:12 to 1:2. If only approximately a ratio with integer values, the slope dimension could be preceded by a tilde (~) character, as SU does for approximate values.
What other types of users want to show a slope value instead of an angle? Civil engineers? They would probably need a much larger base 'run' than just 12.
Do they only dimension a slope relative to the horizontal, or can/should the adapted plugin allow for any reference plane or baseline?
Maybe this ought to be spun off to a new thread..... Not sure how to do that though, myself. I thought there was an option to 'Reply in a new thread' but if so, I can't find it, or don't have the privilege to do it.