In a bold statement, I believe your users will have the same learning curve whetherthey are taskedwithCreo 1.0 Direct or SpaceClaim. In fact, they might as well be one in the same software as the direct modeling is essentially the same. There are niceties in each softwareand all will be a result of how good your users are and how fast they become proficient.
Another bold statement is this. Just as Pro/E of yester-year was a homogenous software suite compared to UG, Catia, SDRC's collmination of other modules and functionality, SpaceClaim appears tobethe more homogenous software compared to Creo/WF5. It has many productivity "goodies" available at the click of the mouse, much embedded engineering reuse data and fast common part/product data immediately available with drag and drop. It just appears to be "faster" to get things done. Now this is a subjective statement, I understand...just my opinion.
As with all things....the devil is in the details. Data management will be a big determining factor. Migration to Windchill is painful regardless. Users will have a long learning curvewith Windchill coming off Intralink. If you can wait until V10 of Windchill then they get to re-learn it once instead of learning 9 for a short time then 10 it would be better.
It looks like migrating the geometry to Spaceclaim will be an easy task if you do nuts and bolts type products. If you create organic things then its all a question of math. I.E. how well will it translate and is it still useable?
And of course...price after the dust settles. Moving/changing/dropping/replacing corporate software is never inexpensive. Fine tooth comb ALL the contracts and licenses you have in place and make sure you do not have to "buy out" of your current situation with company X,in the name of saving money, better functionalitywith company Y, only to find you have a 61 year ROI.