On the limes, I think you may want to try Sudachi, a Japanese citrus with acidity levels in the lime range, but a different flavor profile. It is used similarly.
On the role of different growing Climes, I have compared 'Washington' with established trees that are in a slightly more coastal valley, and ones growing in the foothills of SD county. The one growing in the foothills is not as well established (Sub 8'), and is in a well drained silty loam. It receives regular irrigation, and is a moderate producer of moderately sweet fruit.
The more coastal tree is in an inland valley, also on a slope, in the heaviest of clays, is well established (between 10' and 12'), receives no irrigation, and has exceptionally sweet fruit with an excellent acid balance.
I suspect that calcium is playing a role in this, and will experiment going forward.