If the pine works for you, keep on using it. The aspen won't do anything in a different, better way for you! People that are allergic or sensitive to the pine do better with aspen, but if you don't have that problem...or the chins aren't allergic to it...there's no need to switch because it's going to do the same job for you.
Here I just use pine shavings, no one seems to have any issues with them so there's no need to use something different. I've had to use other types of bedding in the past for certain chins, but those have been few and far between....but it does happen that a chin will have a horrible reaction to pine every now and then. I have wire bottom floors in the cages now so I rarely have any chins with any problems (with the pine...)