Sure, the PCL version might well be sufficient for your needs. However, as you are bound to find out when you create your own PCL class library project, the sub-set of .NET Framework classes and methods that you can actually use in a PCL project is a rather small one. That sub-set is created by taking the full .NET Framework and subtracting out the parts that cannot work on another platform.
The most restrictive platforms are Silverlight and Phone7, they are based on the .NETCore version of the CLR. And Store and Phone8, based on the services available through the WinRT api. Targeting any of these quickly dwindles down the number of things you can do in your library.
The Microsoft.Net.Http package was optimized to still make some of the Http relevant methods and properties available if you are not limited by one of those restricted platforms. You can have a look-see in the packages subdirectory, the System.Net.Http.Extensions.xml files that provide IntelliSense shows you what is possible on one platform but not another. I see:
- HttpWebRequest.AllowAutoRedirect
- AuthenticationManager.PreAuthenticate
- HttpWebRequest.ProtocolVersion
- HttpRequestHeaders.TransferEncodingChunked
- HttpClientHandler.UseProxy
Do note that these properties are mapped with extension methods.