We have refactored GemBox.Spreadsheet 3.5, so it no longer uses constructs that do not work in medium trust environment. As a result, you can now use GemBox.Spreadsheet 3.5 in medium trust security level that is typical for applications hosted in cloud or shared-hosting servers.
We have fully tested support for medium trust, but since many hosting and cloud providers override default medium trust level permissions, there is a possibility that a component might not work in the modified medium trust environment. If that happens, drop as an email and we will investigate it.
You can download GemBox.Spreadsheet 3.5 Free with medium trust support here. Support for medium trust is added in build v1012.
For a demo, see our Web demo which is an ASP.NET application that runs in medium trust.