It kills me to agree with Jutarul, but this is actually a pretty good way to measure it. The whole "If you bought BTC instead of XXXX device in YYY time, you would have made ZZZZ" is ludicrous and goes to show that the person making that argument does not understand how money works.
"Hindsight" wasn't my argument. BFL converts all BTC to USD, thus avoiding all currency risk. Buyers on the other hand preorder with BTC, and have their spent BTC sit in limbo until the product they purchase is finally delivered. True, BTC could have fallen instead of risen, which would have made those who have preordered much better off (and BTC did fall from $12 to $10.50 for a time), but this currency risk is taken on entirely by the customers. The decision to preorder a long time ago, which resulted from a huge opportunity cost, turned out to be a bad decision, but the main reason that decision was made to begin with was because BFL claimed that the delivery date was only a couple months away, i.e. BFL claimed that the currency risk would be smaller than it turned out to be. In the end, BFL was not affected, since it is not affected by BTC fluctuation due to holding USD, those who have preordered a long time ago have experienced a huge opportunity cost, and BFL is to blame. (If you think opportunity cost isn't a real cost, the extra $3,000USD worth of BTC that I have and that you don't says otherwise).
Now, I'm not saying that this is something that BFL needs to repay to those who have preordered. Currency exchange risk is often unpredictable, and something those who preordered (maybe) likely expected. I'm just pointing out that delays that happen when dealing with two currencies that fluxuate against each other do have very real costs, begin just annoyed customers and whining on forums.
By the way, it could have been MUCH worse if BFL had kept all their customer preorder funds in BTC instead, because if people asked for a refund, had BTC lost value, they could refund BTC, and had it gained value, sell it for the USD price equivalent and just return the USD, netting the BTC gains for themselves. It would have been an almost risk-free investment for them.
BTW, did BFL mention whether they are still keeping customer's preorder funds in a separate account? Because until they start shipping products, that money is still technically Unearned Revenue, and does not belong to them. I'm assuming that's what they are doing, since they are an LLC, will have to file taxes, and will have to declare it as such, lest they bring the wrath of IRS auditors upon their heads.