I'm a levergun fan, but have no experience with Rossi. It may be a regional thing, but the I don't personally know anyone who owns a lever-action Rossi. I like the look of their stainless guns, but my Marlin and Henry leverguns have been so reliable that I really haven't seen a need to add any other lever-actions to my collection. One of the drawbacks for levergun makers is that customers don't often need to replace or upgrade guns that run for generations.
I've been considering a 45-70 for awhile, but I'm waiting to see how the new Marlins built by Ruger look before picking one up. Unless there's a sizable price difference, I'll probably stick with Marlin or Henry over a Rossi.