aside from the obvious, what is the...
aside from the obvious, what is the difference between fixed leg loops and adjustable leg loops. do they make a real difference?
The biggest advantage is if you're going to be wearing a different amount of clothing under them. If you use the same harness with shorts in the summer and layered pants in the fall/winter, you may find that the layers make the leg loops too tight.
I agree with everything Angus said but I'll add that I get a better fit with adjustable leg loops more often than not because I have a small waist compared to my thigh girth (damn skiing!!!).