Adam, your ribs look perfect to me!!!
High heat to finish will caramelize the rub pretty quickly, but if your rub has much sugar it will slowly caramelize when smoking low & slow, given enough time. I won't use processed sugars in dry rubs for brisket or pork shoulder...anything that has long cooking times. In fact, I stopped using sugars and started using dried, ground fruits in rubs for years. The natural sugars in fruits seem to caramelize more slowly than processed sugars, so my bark has a nice deep, dark color after long smokes.
Eric