Shining spears will rape terminators/teleporting sternguard/tanks and dreads/anything with an armor value or fewer than 8 models. Just make sure you keep turbo boosting around for the cover save, they're too fragile against shooting and smurfs tend to throw around drop pods so he'll be able to get something within rapid fire range no matter where you hide the spears. Their exarch hits with a strength 8 power weapon at initiative 6, his powers are nifty but not necessary. Giving them an autrarch is like adding two models to the squad. A farseer with fortune means re-rolled turbo boost saves, which is a great way to make your opponent waste an entire shooting phase on one unit. Just don't be an idiot and plop them down next to a LRredeemer, or let them get charged.
If you don't mind shelling out 200+ points (and some cash, ebay is your friend) for a unit and can employ a modicum of finesse in their use then you'll wipe the marines.