The hipshot keys are really nice, and stay in positon well. If you replace your nut with a black graphtech one, the strings will go to tune with equal tension on both sides of the neck and stay in tune better, and will glide between tunings better. I had a graphtech nut made for my favorite bass and like it a lot.
You need to look at the Hipshot Bass Xtenders, that allow you to change tunings of a string with the flip of a lever. Pretty cool. I saw a picture of a bass where every string tuner was an Xtender, but I do not know were that picture was.
http://store.hipshotproducts.com/cart.php?m=product_list&c=6
I would recommend having a separate bass for those different tunings, but if you want to play one specific bass on both types of songs, I also understand that.
I remember, Bryan R. Tyler (a talkbasser) had a picture of an Elrick on his website that had more than one Bass Xtender. My filter will not allow me to go to his site.
Here you go, found it, look at the pictures on this page:
Link Removed
You can find "Bryan R. Tyler" on this site.