A mate of mine ran a terrafirma set up with 2 inch springs and +5 shocks without a problem. All he did was extend the bump stops by an inch to stop the wheels getting too far into the arches and doing damage. In theory then you shouldn't have a problem by dropping the mounts. Also lots of kits for sale in LRO etc advertise 2 inch lifts with 5 inch shocks as do devon 4x4 and gwyn lewis which is effectively the same as 2 inch shocks and lowered mounts.
Harry