Link seems to be broken, but do you think 4 smaller sensors would be significantly cheaper than a 35mm sensor?
Technically it may be a little cheaper for the sensors themselves, production costs and yields tend to go up a fair degree with increasing die size, however that would be offset by increased costs of the sensor read electronics and assembly costs. I'd also assume they'd be a gap between sensors which might not matter for that sort of application because maybe they always interpolate multiple frames. I suspect in that particular case it makes sense because they are dealing with a size well beyond any practical manufacturing techniques for making it on a single die.
Sorry the link didn't work for you, here's a different one about the same story:
And ya I was specifically referring to the cost of the overall sensor. I'm not sure, but I figure since the cost of sensors relative to their size is exponential that combining smaller sensors would be more cost effective. Oh and I was also just curious