Hi Andreas,
Is the concern the fact that the 3-state ADDR pin only gives you 3 I2C addresses? You could either use an I2C multiplexer, or either LTC4316 or LTC4317 Address Translators:
http://www.analog.com/media/en/technical-documentation/product-selector…
I have an embedded board that has 2 separate I2C bus connections. The I2C slave devices have a fixed address of 0x52, so I'm restricted to only 2 instances right now, but I would like to support up to 4. I know I will have to make Linux driver changes…