Umb 7.5.11, legacy site, ModelsBuilder Off.

I can't work out what's missing if, in a partial with all these usings (which are actually being used):-

@inherits Umbraco.Web.Mvc.UmbracoViewPage
@using System.Collections.Generic;
@using System.Linq;
@using System.Web.Security;
@using Umbraco.Core.Models;
@using Newtonsoft.Json.Linq;

I'm having to use JArray to get RelatedLinks as RelatedLinks isn't in Umbraco.Web.Models

And the following won't work to get data out of a Dropdown List Multiple (this is example code from the docs)

@{
  if (Model.Content.HasValue("superHeros")){                                                     
       <ul>                                                        
      @foreach(var item in Model.Content.GetPropertyValue<string>("superHeros").Split(',')) { 
        <li>@item</li>
      }
    </ul>                                                                                       
  }
}

If I ask if(Model.Content.HasProperty("superHeros")) it succeeds. If I ask if(Model.Content.HasValue("superHeros")) it quietly fails as if it has no value, which I know it does!

Any advice would be appreciated.

-Craig