A few thoughts....
Think about why you are adding the IR. For most peopel an IMC is more than enough.
Most people with an IR will not fly in less than IMC conditions(or even VFR conditions, 3K). The thought of 200' approach in a single piston may be out of most peoples comfort zones.
Most airways in the UK are out of reach of pistons.
If its a matter of having it because you have to have it then a MEP IR is the cogniscentis choice.
An IR does allow IMC in Europe and for a lot of countries an IR is required for night flying.