We have a 1999 Disco 2 4.0 with multipoint gas, goes slightly better on gas than on petrol, well worth the cost in my view.
There are issues with running on gas continuously, particularly with the ECU's learning mode, but if you run on petrol round town and switch to gas out on the road, it will be fine.
Multipoint is all you'll be offered these days, get someone that knows the kit and understands how it is supposed to be set up.
plenty of bodgers out there mostly badly fitted coolant leaks hoses chafing on brackets, ecu faults from poor conections and incorrectly connected and effecting the multiplexing systems of the vehicle too