I compared the tech costs of DW vs vanilla. There is no huge difference
There is however a huge difference in the potential economy size.
In Dune you have:
a) spice corp, which can easily be providing an extra 40 commerce+ or so in your capital, which gets multipled by all your boosters.
b) higher tile yields, particularly in the early game, and particularly of food yields from only a few tiles, which make specialist economies much easier to support
c) Bigger economy bonuses from civics, with either specialist economy (meritocracy and faufreluches) or cottage economy (private property + planned economy)
d) High bonus food yields from greenhouse and water refinery buildings.
So tech costs need to be higher than in vanilla to have a similar progression, with the higher commerce amounts.
And many people feel that vanilla tech progression goes a bit too fast, hence why many other mods like FFH have slower tech rates.
I think I would rather increase settler costs and reduce the bonuses from greenhouse and water silo than reducing the prevalence of water sources significantly, but I'd also be happy to leave tech costs for now and experiment with growth reductions instead.
We want a city in any given place (since the AI is bad at city placement and tends to fill up all land tiles with cities) to be at least moderately viable, so I think that changing bonus placement isn't the best way to go.
I'd also be fine with pushing Deep wells back later in the tech tree, which would also help slow early water.
What do you think about the viability of my suggestion in AH104?