With the 9.5 m2 Retro, you have the power to get going early, and a wider board
would get you the most gain but you will need a really big vertical fin (or a very large weed fin if you use weed fins in your area).
Do the sites you sail have plenty of water depth?
The Futura 155 at 85 cm wide gets my vote as the best compromise here.
I think the Shark at 80 cm wide is going to be an improvement over your nTrance (also 80 cm wide) due to the weight difference, but it may not lower your planing threshold all that much.
The Techno formula at 94 cm wide will definitely get you going the earliest of the 3, but as you suggest, it's a formula board and while I'm sure you can make the transition to the wider footstrap offset (same is true but not to the same degree with the Futura 155)
it's not going to be real comfortable right at first.
You will get a bit more range and an easier to jibe board with the Futura 155 so I guess when you look at things from all angles the Futura would getmy vote.
Durability issues would probably be about the same with all 3 boards.
In any event, you are going to have to get some larger fins whichever board you buy.
What fins are you running on the nTrance?
Wider boards with larger fins, rigs with lots of low end power, and good pumping ability are the keys to really early planing.
Hope this helps,