The wife and I were kayaking all day and had to get to the water down some serious two-track in Southern Alabama, and we probably said 4 times "Were soooo glad we had our axles flipped and a 4" lift kit installed!"
These were some serious trials and if it wasnt for our lift kit, we would have never made it.
Are you going to be on trials like this often? That is more of the question. For us it was mandatory, but if it's just a once a year thing, then you might want to save the money. Then again, replacing your scissor jacks a few times will get pricey also.
This obviosly wasnt too crazy of a trail, but if you have a stock height coach, you'd know that you would almost be scraping on this type of two-track and run the risk of tearing something off.