Ask HN: Feedback/advice on an EC2 based startup

I am hoping to get some input for the minds here at HN. My startup can be found at: http://LabSlice.com. It's a solution that allows you to use EC2 for the distribution of thick or thin client applications to customers (ie. send your customer a hyperlink, and it will automatically launch a fully accessible VM for them on a timed-lease). The idea can be extended to anything where sharing of VMs is desirable: training environments, test and lab systems etc.

One problem I face is that I currently require a user's AWS Access Keys (web service keys) to be able to manage their environment. This tends to confuse people at sign-up. I'm wondering if it's a smart or risky idea to give short term trials using my own EC2 AWS environment, or if I should focus solely on those who already know a lot about EC2.

Thanks. SE.