Re: Twice as nice
Yeah, that's called RAID 0, and has been around for a bloody donkey's year.
The problem is that by using 2 drives, you are effectively doubling your chances of suffering a HDD failure, because if you lose one drive, you lose all data on the array.
I suppose what you're proposing is a self-contained RAID0 array in a 3.5" / 2.5" package, which is interesting, but would cost much more than double the cost of the original drive with worse than half the reliability, plus you'd be relying upon 1.8" or micro-drives for your storage, which aren't particularly fast or capacious in the first place.
If speed was that important to you, then you'd be using flash, or if you need speed and capacity, you'd use your own RAID array of either HDD's or flash drives.
So, nice idea, but it fails the reality check.