I am still a huge fan of the 8703e with the scroll wheel. It feels like a shoe box in your hand next to the Curve, but love it nontheless.
I didn't find the transition hard at all when going to the scroll ball. Just be sure to set the sensitivity of the ball to your liking. I overshot my target many times when I first got the Curve.
The ball comes in handy when using it as a mouse while using the web.
Overall, a great upgrade by going to the Curve, but still love my 8703e.
P.S. It's not girly, it's manly and the ladies love it.
