I've been playing games with my Executioners using the Gladius Strike Force, trying to figure out what's the best way to use the new Space Marine Formation. While I really like the bonuses given by the GSF, I keep finding it very restricting. This mostly comes down to the Auxiliary Formations. Many of them are quite expensive to include, and prevent you from adding a single unit of a given type (mostly Elites or vehicles) to your army. Instead, you have to really commit and add a bunch of each type. This is great for theme, but not so much for a well-rounded army.
This got me thinking about whether each Chapter Tactic works better with a Combined Arms Detachment (CAD) or Gladius Strike Force (GSF) as far as building an army to maximize their strengths. Of course, if you are taking two Demi-Companies to receive the Battle Company benefits, then the free transports more than make up for the restrictions. My discussion will be limited to the much easier to field single Demi-Company backed up by one or two Auxiliary Formations.
To review, the benefits of the GSF are the ability to use all three Combat Doctrines once per game, and a 2nd use of the Tactical Doctrine to benefit just the Demi-Company. In addition, the Demi-Company is entirely Objective Secured. With the CAD, only Troops are Objective Secured, and you get to re-roll your Warlord Trait.
Ultramarines
The Ultramarines already have access to each of the Combat Doctrines once per game, so they end up with 7 total uses when taken as a GSF. This seems like overkill, but I think it gives you a lot of flexibility. Most Ultramarine armies aren't going to make much use of the Assault Doctrine, so having extra access to Tactical and Devastator Doctrines is very useful. In addition, Ultramarine armies benefit a wide variety of units, so just about anything you take works well with the Doctrines. While I don't think the benefits a GSF brings to Ultramarines are particularly exciting, I do think they are useful.
By that same process, since Ultramarines already have Doctrines, you won't feel like you're missing out much by taking a CAD. I think the benefits are pretty even for each Detachment.
White Scars
The White Scars lose a lot from taking a GSF, as it limits the number of Bike squads they can take to two per Demi-Company (a Bike squad and a Command squad on bikes), and the only Formation that allows you to add more bikes is the 10th Company Task Force, which brings the ever unpopular Scout Bikers. This really limits the benefits of Born in the Saddle, which are massive and best when used in a bike heavy CAD.
However, Fight on the Move benefits all of the units that you would take in a CAD and makes all of your infantry units a bit faster and able to slip out of assault. It's not a bad benefit on its own, but I feel like the strongest White Scar lists can be fielded with a CAD or with a full Battle Company, where the massive number of ObSec units with Hit and Run will be very hard for the enemy to deal with.
Imperial Fists
This is the Chapter Tactic I have the most experience with, and the impetus behind this article. Bolter Drill already gives you re-roll with most of your bolter shots, so I always felt like I didn't really need the Doctrines. They were primarily useful for getting re-rolls for my Tactical squads' special weapons and my Devastators heavy weapons. Useful, but not really worth the restrictions.
What really bothered me was how much the GSF limited my firepower. I love my Tank Hunting Devastators, but I can only take one squad per Demi-Company. That really cuts down on how much damage they do. The GSF also makes taking my beloved Thunderfire Cannons near impossible, as they only come with three tanks and a Techmarine. I couldn't take my Stormtalons without adding an expensive Stormraven. The one Auxiliary Formation that really benefits from the Imperial Fist Chapter Tactic is the 1st Company Task Force, assuming you take a bunch of Sternguard to benefit from Bolter Drill. However, if you don't have the points to add three squads of Sternguard, you can't add any.
While I think the GSF is fun to play with Imperial Fists, I think that it is significantly significantly weaker than taking a CAD, where you can make better use of the best Imperial Fist units.
Black Templars
The Black Templars really don't benefit from the GSF, as it doesn't allow them to take Crusader Squads. I can't imagine taking Black Templar without wanting to use Crusader squads, so you'll have to use CAD.
Iron Hands
The Iron Hands get Feel No Pain (6+) on all their infantry, which is a big advantage for all of the Infantry in a GSF. However, they also get It Will Not Die on their vehicles, which is a bigger benefit on heavier tanks. You'll only really get to make good use of this if you take a Land Raider Spearhead or Armored Task Force. If you plan to take enough tanks to field either of these Formations, then the GSF is the Detachment for you. If you aren't but still want a few heavy tanks, then you need to take the CAD.
Salamanders
The Salamanders get bonuses to their flame weapons (and melta weapons if you take Vulkan He'stan) and all of their Characters get a free Master-crafted weapon. Both of these abilities are widely distributed enough that taking the GSF isn't very restrictive, and the Combat Doctrines give them re-rolls on the bulk of their weapons. I haven't tried it out personally, but I think the Salamanders are the Chapter that work best with the GSF.
Raven Guard
The Raven Guard gain Shrouded on turn 1 as long as they aren't in a transport. This makes them the only Chapter that actually loses a benefit when fielded as a Battle Company, but doesn't hurt when just fielding a Demi-Company. Winged Deliverance gives some great bonuses to Jump units, and you can only take a single Assault squad per Demi-Company. However, you're probably better off taking multiple Vanguard Veterans with a 1st Company Task Force, as they are much better assault units for the points. Given that Raven Guard don't have natural access to any re-rolls, they benefit a great deal from Combat Doctrines. Therefore, I think the Raven Guard also benefit from being fielded as a GSF.
Those are my thoughts. Have any of you tried fielding your Chapter with the CAD and the GSF? What have you found to be best?