I found the AI not be very helpful.
Like I would jump to each of three squad and very quickly position them to defend the three axis of advance.
However, the AI even though it is covering an exposed flank just likes to turn to the nearest threat. Invariably, those who are covering my back get shot in theirs ... and then me in mine.
I've tried various weapons. Each has its pluses and minuses:
(1) SAW. Great for dealing with a close charge. Not so good for stealth or distance shots. Although it does supress the enemy, it seems that you actually prefer them not going to ground so that you can kill them.
(2) Silenced. Good for shooting from the shadows repeatedly and they don't really pick up where it is coming. You can pick off a steady stream of hostiles provided they are close enough to not consider the low velocity rounds to be bee stings.
(3) Rifle. Good for picking off the enemy as they approach from distance. But it does give away your position and you are somewhat vulnerable in the rush.
I find displacing quite hard. I mean you cannot move backwards very fast. It seem shooting prone it best if you got your flanks covered. However, once you get a red threat indicator, you really need to displace, since you know someone is going to lob a grenade. But it is hard to displace ... it would be nice if there was some type of withdrawal command. Sort of a reverse bounding overwatch. So, one guy could turn run and set up in cover while having his back covered.
Another thing that makes things hard is that they cannot reach your base. (even if you would wipe them out) I found that if you can make it through the initial wave, then going on the offensive and counter attacking may be best. First, when the teams spread apart it is more likely that someone will have field of fire rather than everyone being screened. Second, pushing out seems to have affect of breaking up the rythm of subsequent attacks.
I must say I like the pace and speed of DEFEND; compared to slow and careful movement of fire fight or a mission. I used to play a lot of Combat Mission. DEFEND reminds of a CM fire fight where at close range squads would quickly be decimated in just five minutes. Additionally, the feel is very different than other modes of play where there isn't too much of fire going back and forth ... everything is pretty long range and lethal. In DEFEND, there are lots of burst and suppressing fire.
BTW, I have tried the trick of playing DEFEND in COOP-MP with all AI. You get an extra three men. Additionally, it seems that the attacking AI is not as good as in SP.
Is there any way I can alter the standard defend profile? Generally, the attack seems to begin in 45 seconds. I would love to have say 3-5 minutes and position each team in cover with the best possible fields of fire and protection of flanks. IMHO, this would still be a hasty defense (it's not like in 3 minutes anyone is going dig any foxholes or trenches; or deploy any heavy weapons).
Has anyone made any MEETING ENGAGEMENT type scenarios where the both sides enter from opposite sides of the map and shoot it out? Or how about a CAPTURE THE FLAG where both sides maneuver trying to take a position and then hold it for a certain amount of time?