Lets break down the 6 new Scenarios

I think you're on to something with control casters. Initially in the CID they weren't too suffocating because you required a 6 point lead to win. But when they dropped it down to 5 I noticed the return of the old style of choke someone out on scenario and just stall the game to win, especially since some scenarios it's pretty easy to score 3 on one turn, then pop your control feat, and probably score 2 the next. Wished they would've kept the mercy rule at 6 because even if they went up three, you really had a chance to come back and have a game of it. You were behind sure, but you had a chance. With 5 points though, I find one scenario mistake is harshly, harshly punished. Not quite as bad as mk2, but still bad enough to be a really unfun way to lose a game. Other than that I'm pretty happy with the scenarios. Things like eliminators or min cav are probably going to be really, really, useful to make sure you're covering scenario.

I'm paying more attention to solos and battle engines in lists. Solos allow to score flags without caster and battle engines can score rectangles without the need to drag the caster bubble there.

Irusk2's feat is very good with new terrain placements. As is Hark's pop out of forest, shot and repo back. Tactical supremacy should enable more things like this.

Feat + jam is valid tactic now that point difference is back to 5.

Since zones are futher apart, models are further apart meaning going in waves is harder and threat ranges become very important. The one with shorter threat may not have the luxury of second wave saving him after he gets alphaed. Spd 4 is even more godawful now, you probably shouldn't take melee jacks if you can't speed them up.

Contesting should be prioritized over anything else. Good rule of thumb is to keep something in every zone/flag every turn. If opponent scores on your turn you're going to lose very fast.
The way to achieve scoring on opponent's turn for us is attrition or jam since we lack control. Destroying everything on one flank is a good way to set up scoring, if your other flank remains alive enough to contest you easily win from there.
If possible identify the opponent's weak link in unit types. If he has low number of solos/jacks/infantry, you can focus fire them to render him unable to score certain zone types.

Recursion is absurdly good in 2017. Contesting is easy for those lists so they're not losing on mission anytime soon and over 7 turns it snowballs. You have to kill the recurring part of Fleet/Testament army twice if you go for full length game. Having caster with RFP is close to mandatory now. Hopefully Alexia will be allowed in one of our infantry themes to replicate this.

Assassination is harder to do due to bigger killbox. No side killbox means you can just sit on one side and nothing will happen to you.
Unless caster commits himself to shooting or melee you're not killing him. On the other hand our squishy casters have easier time staying alive.

The math for zones is as follows.

You can reasonably aim to get up to 3 points per turn in every scenario.
When it was 6 point difference you needed to do that twice in a row which was incredibly hard without destroying the opponent's army. Now if you get a good turn of 3 points and opponent doesn't lessen the difference, you pick the 2 points that are easiest to obtain (1 of which opponent can't probably reach to meaningfully contest anyway so you're down to 1 point you have to actually work to clear) and contest the rest and you win.

If opponent scores 1 over you on your turn, he's at least 2 points up the next turn which can turn 3 if he dedicates anything to clear any other zone. And 3 is a good spot to be in as previously noted.
If he scores 2 over you on your turn, he's at least 4 over you already and can dedicate everything he got to clearing that last zone which is usually game over unless you get really lucky on dice rolls.

Would having cheap things like Mad dogs and Berserkers help here? Essentially throw away crap to help with contesting while you focus in on other areas? And of course others have jacks that do such a better job than that.

Yes.

Also, unless they changed it solos cannot score a flag.

Berserker aren't so cheap and throwaway anymore since they cost only 1 less than Marauder.

Cheap stealth solo and units like elims are good contesters. Generally they can't be removed by shooting and because they take very little board space it's easy to put them somewhere hard to reach behind terrain.

Also Ambush is really good now for both contest and offence as some of zones/flags can't be scored without being in Ambush charge/shoot range.
Have you played against Troll bears yet? Those things kick ass.