I'm an IP and my "reward" for winning the first mission will apparently be the more difficult, but by all accounts more fun mission, Under Siege. I have been studying the map, the turns, and the threat buildup while also reading other players' experiences online.
The majority of the opinion claims that the AT-ST decision is a bad one. At first glance and upon planning, I agreed. After reconsidering the issue some more, I wonder if you built a strategy around planning to use it, whether it could be the better choice. As I began to plan this mission, I felt very constrained by the 2 open groups. You will have to devote one of them to your infiltrators if you don't go AT-ST. Furthermore, you will have to pay out of threat to get them in there. Does a group of Trandos or whatever cause that much havoc that it's worth: A free (14 threat!!!) figure deployment, using your saved up threat (that you would need to spend on your infiltrators) on other units, and an open group space that you don't have to use on your planned infiltrators. All three of these are worthy considerations, but upon planning for this mission, I actually think having to devote an open group may be the biggest reason to go AT-ST. Everyone keeps talking about using Nexu or using an "officer train" for you know who, but you can't make all of this work if one of your groups is Trandos or Guards for the inside job.
Obviously the main drawback to the AT-ST is that it can't get indoors, but if you parked it at the east outside door, it has fairly good (but not total) LOS on the first two rooms. Could you not implement a strategy that took advantage of this by trying to rush the back rooms knowing your AT-ST will help with the first two or is the AT-ST really not worth all three of those considerations?
Please note that I have not played this mission before which is precisely why I am asking seasoned players for their experiences. Maybe the answer to my question only becomes clear on a playthrough. Thank you for your time.