If x10Hosting offered free vps, then x10Hosting would probably struggle to fund this and ensure the Terms of Service is not abused. Therefore, I really do not see x10Hosting offering free vps - the current vps prices are already very cheap.
A Trial VPS would be great! It would allow users to get a feel for what x10's VPS's are capable of, whilst showing the end users just how reliable and good the service is. Many people (Including myself) always prefer a trial version of a product before committing to buy. For the amount of effort it would take to create it and maintain it, it seems like a sound investment to install it.