The next renovation of the approach to the Asymmetrical Missions represented at missioncatalog.com will be to develop a broader range of Secondaries, and enable players to choose from a set # of them for each mission. So, instead of more restrictive and typical ones, you'll see perhaps 6-7 to choose from, and select the ones that best suit the match-up (which your opponent will of course be doing also).
There's an important nuanced difference to be found between progressive mission scoring (which the asymmetricals espouse in large part) and choice-based mission design.
Let's jury rig an example for comparison here ...
1) Asymmetrical / Choice-Based Mission ... Choose either to have your objectives count for X points each at game end, or Y points per turn. Your opponent chooses independent of you. Further, choose what secondary goals you're pursuing (i.e., KP, Linebreaker, Warlord, Quarters, whatever). Select 2-3 from a list of 7. Again, you're choosing your mission independent of your opponent.
2) Progressive Scoring Only Mission ... Both players accumulate points on a per turn basis or throughout the game along identical scoring metrics.
The difference here should be more clear when presented in this way, but it's an important one in assessing the intent and purpose of missions. One of the key goals behind Asymmetrical Mission design is the avoidance of harm to the status quo "power lists." If missions are designed that broaden the competitive field, all is well. If all they do is change the competitive field, you're simply shifting the bar to a different status of what a power list is.
These differences are important, because there's been a lot of inspiration throughout the community from the mission catalog - across forums and blogs everywhere you're seeing a lot of really creative and productive thinking toward how to build a better mousetrap ... how to make missions that are more effective at making the game more interesting for players.
THAT SAID, keep in mind as you are designing your own, and as you are talking about the ones we've built, the key for these missions is NOT the progressive scoring in and of itself. The key is the freedom of choice for players, so that the actual mission you are playing is determined based upon the match-up, the round, etc., and not predetermined in a very fixed way in the mission primer.
By making mission design partly in the hands of the players, and not determined until you actually start the mission, you prevent gaming the system more effectively. You also demolish the notion of a predictable meta and of knowing what list you should or shouldn't take to do well.
In this way, a broader range of list styles are activated as able to do well without harming the effectiveness of the lists that are "best of" by the nature of the game designed by Games Workshop. In the same way that you do not want to completely abandon the rules of the game, you do not want to structure a tournament that completely abandons the naturally good lists of the game. This is true both because you do not want to harm one set of players' investments just to give other players a chance (ending in a net-zero change and no true improvement), and because you want to remain respectful of the game you're choosing to play / put on an event for.
Food for thought.