I know it's crap shoot, but maybe you can just order the Nikon Fieldscope ED Spotting Scope (25 - 75X )from Cabela's, and because of their liberal return policy, return it if you are not satisfied. Then try the other brands until you find the one you like. A bit bizaar, but might be the only way to check them out. On such a substantial investment, you may have to take bizaar methods to find what you are looking for.
Click here:
http://www.cabelas.com/cabelas/en/templates/product/standard-item.jsp?_DARGS=/cabelas/en/common/catalog/item-link.jsp_A&_DAV=MainCatcat602006-cat20762&id=0041013712621a&navCount=2& podId=0041013&parentId=cat20762&masterpath id=&navAction=push&catalogCode=XG&rid= &parentType=index&indexId=cat20762&has JS=true