I still hesitate to use ViewModels instead of Model for the View

Wether I use Automapper or manual matching, which does not play any role.

All data for ReleaseViewModel must be the first in Release because it is filled with a data access layer. 90% of my model is like that. Why does overhead duplicate everything?

What about the KISS principle and add-ons?

Of course, every tool is for its respective task, but very often I read on SO that not using ViewModels in asp.net mvc is NO-GO.

Where to draw a line? Should I use ViewModels when they differ from 50%, 75% or 99% from my models?

I have a Release model:

 public class Release
    {      
        public int Id { get; set; }       
        public string Name { get; set; }
        public string Author { get; set; }
        public DateTime CreatedAt { get; set; }
        public int FailedTestsCount { get; set; }
        public int SucceededTestsCount { get; set; }
        public int SumTestsCount
        {
            get
            {
                return SucceededTestsCount + FailedTestsCount;
            }
        }
        public int SumTestingTime { get; set; }
    }

a viewmodel ReleaseViewModel:

public class ReleaseViewModel
{
    [HiddenInput(DisplayValue = false)]
    public int Id { get; set; }

    [Required(ErrorMessage = "Name must not be empty.")]
    [StringLength(30, ErrorMessage = "Enter max. 30 chars for a name.")]
    [Remote("ReleaseExists", "Release", ErrorMessage = "This name already exists.")]
    public string Name { get; set; }    
    public string Author { get; set; }    
    public DateTime CreatedAt { get; set; }    
    public int FailedTestsCount { get; set; }    
    public int SucceededTestsCount { get; set; }    
    public int SumTestsCount 
    {
        get
        {
            return SucceededTestsCount + FailedTestsCount;
        }
    }

    public int SumTestingTime { get; set; }
}