Has anyone that shoots Nikon every used both these lens?

I am just wondering if anyone out there (pro or otherwise) who shoots with Nikon (DSLer’s in particular) and owns both the 50mm f\1.4 and the 50mm f\1.8 can give me some key differences when out and about, shooting?
What I mean is: I am wondering what it is like to have both lens and shot with both for more then just one or two times… I have demoed the 1.8 and really can’t see much of a difference, but that was in a store.
I am asking because I use the 50mm f/1.4 all the time when I am being “artsy” and would love to get another two for my other two camera bodies, but have a hard time finding good condition ones and I don’t want to pay new if I can avoid it, mostly because all the camera stores in my town suck butt in a major vampire kind of way and Adorama and B&H don’t have used ones… but Adorama does have three used 50mm f/1.8’s and two 85mm f/1.8’s, both of which always get the highest marks and they are dirt cheep (as far as Nikon Lens go.) So if the 50mm f/1.8 or the 85mm f/1.8 are as good, if not better, then the 50mm f/1.4, I am just going to buy the three 50mm f/1.8’s.
I am attempting to create a stereoscopic image involving some techniques me and my friend have created, and obviously having two of the exact same lens is beneficial!

Just to clarify, I am not looking for the technical specks, as I am more looking for the experiences of both lens… if that makes any sense, as in; “Would you replace the 50mm f/1.4 with the f/1.8?”