I don't even think I'd want to go up that high. 3" is such a perfect number, it increases your approach, departure, and breakover angles without making you too top heavy.

Look at how well Land Rovers, Discos, Tacomas, and Xterras do with just a 3" lift. And look at the way rock buggies are being built now. Instead of tall and narrow, they're getting short and wide.

A tall offroading vehicle can fit big tires and straddle big rocks, but stability is a very underestimated factor in 4-wheeling. A good driver can use correct wheel placement to avoid having to straddle big rocks, but there aren't many ways you can use wheel placement to avoid off camber situations.