This is spot on. I would definitely not recommend more than 3 hops with 802.11n hardware, as in my own experience, a network with 3 hops is no longer able to support even approximately 75mbit of SpeedFlex throughput from the edge back to the ZoneDirector, which is starting to go into the territory of slow wifi.
Another technique worth mentioning that isn't described in some of the older meshing Best Practices guides is the new "eMesh AP" mesh type. Basically, if you wire up an island of outdoor AP's (for example, just wire one T300 into another T300), they will form an eMesh AP, where one AP is a normal mesh node on the same channel as the other mesh AP's, and the other AP gets to pick its own channel and not share airtime, using the wired link to the other AP as the mesh backhaul.
This technique does not result in the full 50% degradation in performance per hop, and might be more practical. If you find performance too slow, it might be worth trying to add an eMesh AP somewhere in the middle of your mesh.