I haven’t upgraded to MonoGame, but XNA has Reach and HiDef. Does this only effect shaders? Is Reach shader model 1/2? HiDef is 3++? Is there any reason we need shaders, as I tried running an XNA project on an old WinXP computer with an integrated graphics card and it wouldn’t run.
DirectX version of monogame project requires Shader model 4.0, thus DX10.
MonoGame on Windows uses DirectX11, which is not supported on Windows XP.
To get anything on screen, you need at least a basic shader. MonoGame supplies several, so you need to write your own if you want a special effect.
Did it change with 3.5? Because I am pretty sure (I mean absolutely sure) that 3.4 with use of SM 4.0 runs on DX10 without issues.
MonoGame has used DirectX 11 since I implemented the DirectX implementation in 2012. It has always used DX11.
DX11 however works on GPUs that only support DX9 or DX10 features and on Windows Vista, Windows 7, Windows 8, and Windows 10.