Actually part of the OVA (more "realistic" one as 
you put it) is also told in the RK TV series. 
(I'm avoiding the differences in the American 
release because I haven't watched any of the 
videos that have been "worked" on over here). But 
most of the OVA is background material for RK.

Like Atiya said, there haven't been too many cels 
from the OVA (or OAV or whatever!) out on the 
market. I've only seen a couple and they go 
quickly!

I'd like to have cels from either, myself ^_^

Wendy