Just wondering what you guys think on the subject - specifically, do you get more realism out of either?

I've only primed black, painted gray/rust and then sanded the high points to expose .... I just ordered a bit of the AK Burnishing Fluid to maybe give it a whirl.

For North Africa/Tunisia Tiger I for instance, wouldn't the burnishing look TOO rusty for that environment?

I know there are experts on here who can comment --- thanks again, you guys are awesome

I do exactly what you do.
I have read a number of times that burnishing fluids can be corrosive and damage the tracks a number of months/years after the model is completed. Not sure if its one particular make or all of them.

I have done both and both methods have been effective.The burnishing fluid is tricky in that the tracks need to be absolutely clean or the reaction wont take place,I scrub with acetone.One time it rusted just right,another time it was blotchy,had to touch up with paint anyway.For me the paint has been more reliable,plus that fluid aint cheap.

Oh,and the one that came out very good was for a Tunisian Tiger,remember the fluid doesnt rust the tracks,it turns them a brownish color which looks prerry good

I have heard of people using CLR lime and scale remover from the grocery store with good results. I haven't tried it myself yet but I have a bottle to try it with.