Just a heads up: The Minsky project is probably the tool to use for anyone with the DE skills required to model Safecoin. I believe there is some work towards modelling BTC with this award winning tool as well.
Usability is very important to the success of a currency
I think @Traktion has the right idea that whatever solution is chosen for divisibility that it be simple. I would go further and say that is is absolutely vital, in that If the average person cannot wrap their head around how the currency works regarding divisibility and if the currency does not follow normal divisibility rules then it could be argued that it will fail one of the three functions of money: as a Unit Of Account. If the desire is for Safecoin to serve humans as a Unit of Account and become more than just a hidden token used internally by the network for allocating resources, then the divisibility of a Safecoin will almost certainly need to be easily understandable by non-technical users. There is lots of good discussion around regarding crypto currencies as a unit of account and the importance of usability (such this and this to pick a couple. “unless consumers can get their head around value, adoption will be extremely limited”).
If a signed StructuredData (currently called a “Safecoin”) is indivisible without a complicated work around then isn’t it the natural “lowest money of account”, like the “Satoshi” is to a Bitcoin or the “Mill” is to the $USD? Say it was renamed (I’ll pick “Irvineoshi” for fun and giggles) then what we currently understand as a “SafeCoin” could be 100, 1000 or some other intuitive multiple of Irvineoshi’s. This is what I understood @Traktion to be suggesting above. It would follows that 32 bits ~4 billion Irvineoshi’s may not be enough, and the 1:1 MaidSafecoin ↔ One StructuredData “Irvineoshi” swap would have to be revised maybe even floated to avoid a crowdsale investor revolt. However the reward to simplifying divisibility would be give “SafeCoin” the chance to be adopted by normal people for wider use as a currency and not just serve as an internal resource allocation token.
Standing by to hear all the technical reasons why this is a silly idea :-).