The Sports is a poor mans Range Rover on a Disco 3 chassis, not the real deal like the vogue. The Sports is also not as off road capable like the vogue or the disco for that matter.
With LPG, I've been advised by numerous Land Rover mechanics to avoid the older LPG systems altogether and to go with the injection type as a minimum.
Reason being, the cylinder heads will not tolerate the higher operating temperature for the long term, with warping and cracking being the end result. Don't quote me on this as I've never had or intend to get it, just what has been explained.
The Bosch motor is definetaly a better engine and to drive, but can be slightly more complex to fix due to the extra electronics involved I. e O2 sensors.

