Coding Assesment Tests Alternatives?

I've taken many coding assessment tests in the past; I've designed a few; and now I'm deciding if I should issue code tests to my own candidates. Here are the concerns I have with code tests.

1) Code tests are generally poorly designed - unless a great deal of time is put into developing them and with a clear idea of what the test is trying to ascertain.

2) Code tests are subjective - there are so many programming philosophy's and opinions out there that I don't think any two graders would agree on the quality of any piece of code unless they agree on exactly what the code test is designed to ascertain. In my experience, code test graders are just told to "give an opinion" on the code.

3) There doesn't seem to exist much research showing that code tests result in better employees. Please post them if you are familiar with some work I would like to give them a read.

4) It is easy to cheat on code tests - online code test taking services or having a buddy that already took the test are real threats to test subversion.

5) The question "How many good candidates am I also eliminating with my test?" is a legit question.