Observations
In intruiging game, but it did raise a number of questions:-
1) We kept the contingents 'hidden' throughout. This seemed reasonable and added some spice to the game
2) In the end-of-turn reveal, formations were being deployed forward of their marker, which allowed them to get into range. This offset the apparent disadvantage of not being allowed to move and fire.
3) However, we did not allow sustained fire - from a hidden location under E:A rules, this could be really devastating. (we have agreed to refight this using the same armies with the roles reversed, and I am not looking forwards to the Supa Stompa being revealed!)
4) One quirk was that this did mean markers could be hidden behind terrain (and thus impossible to spot), while the formation deployed forward to a point where it can shoot. This seemed a little problematic
5) End-of-turn #1 found the big KoS still broken - who makes it's withdrawal? We assumed this was still 'the attacker' (otherwise the effects of 'panic' would be negated.
6) What happens if an enemy formation approaches a marker? We finally came to the view that they ought to have a ZoC, say 5cm, penetrating this results in an automatic reveal of the relevant formation and prevents further movement. If the marker is blank, then the enemy may try to spot some other marker.
7) We also came to the conclusion that 20cm deployment from the marker may be too much lattitude - perhaps 15cm (or the big bombardment template) might be more appropriate.

We were unsure what to do post turn #1 with a partially revealed army. We came to the conclusion that it makes a better game if the 'end-of-turn-reveal' is continued throughout the game. So the 'attacker' must follow the normal activation rules with all known formations, but may opt to reveal any number in the end-of-turn phase (in preparation for the following turn)
9) We did come across an intruiging issue. When the Big Blitz brigade assaulted the Devastators in turn #3, the nearby tacticals could have been positioned around the rear of the BBB to get cross-fire, but in a postion that lay under the path of the BBB. When revealing formations, in addition to the current restrictions we felt they should not be put anywhere just traversed by enemy troops.
10) The Marines were a bit cautious in their deployment. More by luck than judgement they were deployed on the extreme edge of the effective range of the Ork army, and a long way outside any foot-sloggers capability. Combined with the concealment rules this made it much more challenging for the Orks. However, without other incentives there is no reason for an Attacker to risk his forces, while the Defender can then only engage with a small portion of the army. (this is a strategy straight out of Sun Tzu)
As a compensation, it could be appropriate to put objectives on the road at fixed points with variable values to each side (increasing for the Defender but decreasing for the Attacker as they move further from the Defender's starting point), and also give the Defender points for exiting unbroken ground formations off the opposite end of the road. This should force more tactical decisions on both sides and make for a better game
10) I am unsure how balanced the Victory conditions are. While on the face of it, the attacker is fighting with an army 2/3 the size of the enemy force, positioning the attackers at a distance from the defender reduces the odds to about even, and so the scoring system would actually seem to favour the attacker!