"Some providers may indicate that they already provide a SIM capable of switching between several networks. This is absolutely true, however, what is not made clear in some cases is that an outage of the MNO with whom the SIM is hosted would mean that the SIM cannot 'lock onto' another network and is in effect rendered incapable of signalling due to an outage of a single supplier."
I think many don't realise this; that the 'multisim' type of product can only help with day to day signal strength; not outright network failure. Interesting post as ever Joe, although I can't see manufacturers rushing to implement this, I wish they would though; for example I have a GPRS only site which fails every year when the Glastonbury carnival (with their temporary phone masts at full blast) rolls into town. Ultimately the customer will not pay for dual path; but a quick switch to a competitors network, just for 3 days, would cure this.
Also, as I have mentioned before, a local town to us (Burnham) had no vodaphone whatsoever for 5 weeks earlier this year! So it is a real problem.