The allegiance to single engine instrument flying is generally the domain of the inexperienced; those who simply don't know better yet.
I think it is much more to do with cost actually.
I would much rather fly IMC in the modern G1000 C182 that I do for example with its solid state AHRS
and vacuum pump driven back up AI, backup battery for the essential systems and all the other trimmings that a modern IFR certified GPS/EFIS system comes with than the vast majority of shabby twins you see lying around in the UK which cost a lot more and are more complicated to operate. Although Guppy you quite rightly warn against using aircraft with single power sources for the instruments in reality few people actually fly IFR regularly with just one vacuum pump even if the aircraft itself has only one engine. I find it ironic as well that you criticise the Cirrus when in fact the latest versions have excellent system redundancy, the G1000 system for the Cirrus for example has two separate AHRS systems. They are designed to fly IFR safely and can so, which has nothing to do with idiots flying into thunderstorms or getting disorientated. 737s have crashed due to pilot disorientation just as Cirri have, it is not usually the aircraft's fault.
I personally think the Cirrus is an excellent design and has really improved the piston end of the GA scene in the US in terms of the quality of the aircraft available.