We'll have to agree to disagree then. With my controller's hat on it's VFR for simplicity every time.
From the pilot side I'd agree that this does seem to make life easier - and I've had it confirmed by East Mids in the past (transiting in a slight hurry in a twin), when advising that I could transit IFR if it would make the ATCO's life easier to open up the whole zone rather than just the VMC bits: "Actually, I'd prefer if you could ask for VFR - it means I can push you around a little bit more". And, oddly enough, he didn't, very nice quick crossing it was too. As indeed I had a few months later, again transitting EMA on the same track, this time rather IFR in light icing, and a very quick service with only a couple of new headings.
The other thing to consider is what sort of service you'll get OCAS if IFR. In my experience so far calling up for an IFR transit tends to rather increase not only the chances of a RIS before entering, but also being asked if I'd like a service when I leave CAS. EMA again a good example, they're very slick at this. Bear in mind that ATC have no requirement to
offer a service on leaving CAS, so it's nice when they do.