I personally would not touch them with a barge pole, especially if they are double and treble shifting.
All LPG articulated machines suffer the same problem when worked hard, they overheat! The worst is the Flexi.
We had some at a customer who manufactures packaging and they used to get that hot we had a couple catch on fire.
The problem is they can only fit a relatively small engine because of size and there is not a lot of room around the engine for cooling, these machines also weigh aroun 6 ton so the engine is worked hard and there is a lot of hyd heat build up as they are hydrostatic.
My customer now uses electric Aislemasters with large capacity spare battery's and we have no issues.