I've used them w/ proxies my last 6 games and found them pretty underwhelming. It's a shame their abilities were changed. Their current ability almost never applies, and doesn't do much even when it does proc. Their base stats are barely worth 5 points, and the ability isn't worth 1. Sure, it has a chance to screw an attacker over completely (if your opponent is a dolt or unlucky) but most of the time it doesn't apply. It's a reactive ability on a 4 movement unit, which means the opponent will almost always get to chose the conditions under which he will have to take the panic test. He'll charge something into them that has good morale, or avoid them and their 4 movement entirely. Their attacking ability is on par with that of ranged units. Adding an attachment to them seems even worse - 9 points for them w/ ramsey. Probably the least cost-effective combination of unit/attachment in the game, honestly. Roose w/ them is just about as bad. You're WAY over-paying for a unit with mediocre stats, and abilities that rarely apply, and do pretty little when they do. Maybe other neutral attachments to come will make them better, but I doubt it.
Bolton armies need to be fast and hit hard IMO. This unit just doesn't sync up well with them. They don't even seem good as a neutral unit in another army - Starks have Tully Sworn Shields, and Lannisters have gaurdsmen / captain, both of which are better for holding objectives.
Will continue to test them, however my expectations for them are low. It seems like they don't even hold objectives well.