I haven't read the rest of the thread. Sorry if this repeats something already said. But here's the thing. SIDS, while tragic, awful, desperate for the families affected is an incredibly rare occurance. I do know a family who has been affected.
Around 700,000 babies are born each year in the UK. Around 300 children die from SIDs each year (FSID 2010). Or 0.04% of births. 4 in every 10,000 born. As I understand it (disclaimer: I am no expert and happy to stand corrected, but this is based on my own research) there is a significant link to certain behaviours, including smoking, but an even lower risk for families who do not meet the highest risk profiles. The highest risk factors are: being a mother under the age of 20 at the time of the child's birth, the child being a boy, the child being born before 37 weeks, the child being born at a low birth weight (less than 2.5kg). Now, I have never been able to find statistics that give you a % rate for children who meet none of those criteria (including those who have non-smoking parents).
Having considered this information, and decided that all those highest risks were not relevant to my 2 DCs, I concluded that our personal risk factor was far far far lower than 4 in every 10,000 and therefore a risk I was prepared to accept for my children. Both mine, moved out of 'our' room at around 2 months of age (even, shock-horror, without using one of those Angel-Care movement mats, which IMHO are are a marketing wheeze aimed only at making money for its makers and not at all related to keeping children who would otherwise be at risk of cot death alive).
So, if it works for you and you are not high risk then it is your choice and one that I would support.
This is not to criticize parents who follow the advice - everyone has to define their own levels of risk when it comes to parenthood and we are all comfortable with different things. I am quite relaxed but I have a lot of respect for those who are less so. It is a personal choice we make. But you shouldn't be made to feel guilty about the choices you make, particular (IMHO) about very low risk activities.