AnomanderRake wrote:
To my mind the issue with things like this is that they add extra rules to the game without making it much more interesting. The turn structure of 40k (run through the checklist of "have I done [thing] with [unit]" for every unit in the army two to four times a turn) is annoying enough without splitting the checklist up further, and as other people have pointed out further up the page the problems actually solved by alternating activations are kind of negligible.

Games that do alternating activations tend to have simple single-step unit activations as opposed to the "do thing, wait for other units to do that thing, then do another thing" tangle that is the 40k turn. I'd suggest starting the alternating activation discussion by looking at how the phases that make up the 40k turn could be compressed rather than slapping an extra batch of rules on top of an already somewhat unwieldy system and hoping for the best.

As an example, the order system from Bolt Action:

When giving a unit an order choose from the following six:
Fire: Stand still, fire at no penalty.
Advance: Normal move, fire at a -1 to hit.
Run: Double move, fight a round of combat if you come into contact with another unit during this move.
Rally: Remove pin markers
Down: Hunker down to avoid incoming fire, remove fewer pin markers
Ambush: Hold position, fire at a -1 to hit if an enemy enters your line of fire later in the turn.

Because each unit is doing exactly one thing each turn rather than doing somewhere between one and four depending on the circumstances the whole thing is a lot easier to keep track of, especially if you're expected to pass priority a lot during a turn.

 BaconCatBug wrote:
It has the same issue all alternating action systems have, it benefits MSU spam and not much else.

I have yet to come across an alternating system that fixes that issue without some form of resource tracking that bogs the game down horrifically.