I don't think rollerskiing destroys technique at all. Maybe it requires 5-10 minutes first day on snow to adjust kick, but other than that, technique is usually improved dramatically, due to strength/balance gains. ...
Possible. ...But the typical ski has not been HELPING ones kick all during training. It's been impairing kick and then one has to become reacquainted with correct kick. Big difference for such a technique sport.
Of course it depends on if your race course rewards technique or doublepoling... Few reward striding to any noticeable extent. Ha!
I agree that rollersking in general can help w strength and balance. Not strength of legs however. Well, I suppose that one could remember to do it right, but it would be kind of forced. The device would not help or hinder good technique.
Cat Skis reward good technique and discourage bad technique. You cannot overkick them. If you try to underkick or overstride you will be sorry. I kinda like em. But I like striding.