Gosh, I don't think I'd risk moving it at that size. It looks pretty happy and healthy. Water must get through the decking to the roots of the tree doesn't it? Citrus have a large mat of very fine feeder roots near the soil surface. Moving a tree that size would almost surely kill it.
Maybe wait until you get a ripe fruit to taste and then decide if it's worth the risk. If it has lousy fruit, no worries but if it produces really nice fruit, I'd be inclined to prune back the pecan tree and leave the citrus tree where it is.
