I appreciate that the IMC is not a patch on the full IR difficulty wise
That depends where you do it. Some teach the bare bones, some a whole lot more. I was flying SIDs, DME arcs, proper hold joins and every approach you can think of when I did mine a few years back. When I started "IR level flying" it wasn't some magical, huge change in standard all of a sudden. Whilst the IMC rating is a valuable qualification, bear in mind that none of the training will count towards an IR. This is a JAA idiocy; it would ALL count towards an FAA IR.
You don't particularly give the impression that you're firmly aboard the ATPL gravy train, so if all you want is an IR, just do the IR theory; it's about 40% of the work of the ATPL exams.
There's an EASA working group currently looking at IR requirements. I believe one aspect of that is dicussing the current enforcing of 50hrs training on everyone, regardless of experience. Some might need more than 50, but there are plenty of experienced IMC holders for whom 15-20hrs would probably be quite adequate in terms of brush up for an IR test. I wouldn't expect to see any change in the immediate future, but there is change on the horizon.