4-3 with the 4-4?

We have been a straight 4-4 cov. 3 team for the last 3 years. I am looking at going totally to the 4-3 or integrating it into what we have been doing. Any thoughts on this? How do the techniques and teaching carry over? My concern with using both is that, as I see it, the same position could have very differnt responsibilities with both. I don't want confusion! Any ideas would be appreciated.
Thanks,
Mike