Well My Esprit turbo U.K version with Renault box the reason I changed to injection is I'm using esprit all year, so I thought it may better economy, more power, even winter with cold weather easy to start ...
I think as Chris said it's easier to sell and buy SE/S4 .. if tax is not issue.
In denmark, it will cost the TAX twice as much what Esprit cost in U.K.
So, For me it will very expensiv to swap SE or S4.
After 6 months with injector, I had some problem with e.g. O2 sensor, commection problems...., so it's Not better reliability/maintain than Carb. !
The power issue, It's much power,so when the road is wet/snow must drive safe !!
If your Esprit has Citroen gearbox, then you need to check the parts list etc...
to se the differece between citroen V.S. renault !
I hope it will help !
Y.Hotta