In a perfect world the BFL ASIC products are a no-brainer.

Consider the mining pool "ozcoin" (I have no connection with it)

As of the time of writing their site https://ozcoin.net/ shows pool metrics of:
Pool: [ 1,511.46 GHash/s | 273 Users | 616 Workers ]     Server Time: [ 2013-01-13 04:17:16 CET ]

Their 1511 GH/s is almost the same as one BFL ASIC mini-rig which costs US$29.9k
http://www.butterflylabs.com/products/

Checking out http://blockorigin.pfoe.be/top.php shows ozcoin hashing 120 of the last 2016 blocks (basically during the first fortnight of 2013).

So: 120 x 25 BTC x 13.50 (avg fx rate) = US$40.5k in two weeks!  Assuming no downtime, but fees would probably cover electricity.

So a BFL mini-rig is a money-printer - in a perfect world. The challenge is obtaining one first, before they become "widespread". The decay in profitability is proportionate to the rate at which similar machines enter the market and become actively mining. The landscape for bitcoin mining will be completely different at the end of 2013 than the beginning.