As Arthur Y-S says, try it out. I did some time ago, and felt it left a lot to be desired.
I also use Alias and Rhino, although recently less of Rhino -but it is an excellent too at a great price. However, what I find for my process, if you want to be primarily inside SW most of the time, is to only make the primary surfaces in your choice of surface modeler. It is then very easy to import iges or step files into SW and to update them with revised surfaces later. Yes, that is nowhere near as wonderful as having it all inside SW, but it works. I do this in part because I want to have as much as possible parametric, as that is the ultimate speed advantage at the back end.
Also have a look at Solidthinking.com. They are marketing/competing with StudioTools these days, and you can download a demo there too. Although I like StudioTools, it is bloody hard to remember when you do not use it every day. Solidthinking looks like it may be a little easier, and also seems to have a more sophisticated history function (that is what is missing completely from rhino).
Of course, if you are just looking to do fast, time sensitive concepts (not spending much time on accuracy, only a visual sales job), I think Rhino is a great choice for ease of use, and price. That is what I often do.
Good luck! Dan