Thanks for the EGNOS information, Peter - that explains a lot. But yes, I also note m_j's point about 'head down' button pecking. It's something we specifically address during training for flying in certain environments.
Given how similar certain intersections both sound and spell quite similar (e.g. in the south of France), if given a direct, you can enter it but confirming the spelling can be awkward - so commonsense and situational awareness to avoid a Gi-Go error is, as you rightly say, of paramount importance. Presumably airlines have SOPs, but if directed to an unfamiliar intersection, it would seem prudent to use HDG rather than NAV until the new point has been confirmed?
Back to the IMCR. One of the current IMCR benefits is that a PPL holder in the UK may fly VFR above cloud, which rather stumps the 'must only use GPS as a back up to visual navigation' luddites at a Certain Aviation Authority who regard it as a tool of Satan. Under EASA, that well-loved SAFETY agency, plain vanilla PPL holders (or LAPL holders) won't be restricted by the ANO criteria applicable to UK PPL (or JAR-FCL) PPL holders without IMCRs / IRs, so assuming they can find suitable holes at both ends, in a couple of years there are likely to be a lot more pilots navigating with non-IFR GPS above cloud than there are at present.
As I understand the TSOs, 'IFR' GPS approval applies to the entire system, including antenna and external feeds, but applies only to en-route IFR cruising and terminal approaches (subject to additional TSO requirements). So if you're flying under VFR and navigating above cloud, you don't actually need an 'IFR' GPS. But what about the IMCR pilot climbing up through cloud to reach a VFR level, or descending below it at the other end? "No, I just note the heading and ignore the GPS until I become visual" Oh really?
As they do with their own SatNavs in hire cars, many pilots are going to prefer to use their portable GPS units in clubs' rental wreckage and the CAA will have to accept that 'VFR' GPS
is going to be used more and more often as a primary navigation tool.
"Fly and navigate visually, only use the GPS once you have verified its accuracy against something else, and cross-check regularly", as SSL 25 puts it, is going to be observed less and less often in future.